Telecommunications

2022-06-21T04:29:42Z

2605:A600:1D05:AFA8:0:0:0:1: Created an insightful write-up.

{{short description|Transmission of information electromagnetically}}
{{for|the song by A Flock of Seagulls|Telecommunication (song)}}
{{Use dmy dates}}
{{Use British English}}
[[File:Erdfunkstelle Raisting 2.jpg|thumb|upright=1.5|[[Earth station]] at the satellite communication facility in Raisting, Bavaria, Germany]]

'''Telecommunication''' is the transmission of information by various types of technologies over [[wire]], [[radio]], [[Optical system|optical]], or other [[Electromagnetism|electromagnetic]] systems.<ref>{{citation|title=ITU Radio Regulations|chapter=Article 1.3|chapter-url=https://www.itu.int/dms_pub/itu-s/oth/02/02/S02020000244501PDFE.PDF|publisher=[[International Telecommunication Union]]|title-link=ITU Radio Regulations|archive-url=https://web.archive.org/web/20150319031957/https://www.itu.int/dms_pub/itu-s/oth/02/02/S02020000244501PDFE.PDF|archive-date=19 March 2015}}</ref><ref>Constitution and Convention of the International Telecommunication Union, Annex (Geneva, 1992)</ref> It has its origin in the desire of humans for communication over a distance greater than that feasible with the [[human voice]], but with a similar scale of expediency; thus, slow systems (such as [[postal mail]]) are excluded from the field.

The [[transmission media]] in telecommunication have evolved through numerous stages of technology, from [[beacon]]s and other visual signals (such as [[smoke signal]]s, [[semaphore line|semaphore telegraphs]], [[signal flag]]s, and optical [[heliograph]]s), to [[electrical cable]] and electromagnetic radiation, including light. Such transmission paths are often divided into [[communication channel]]s, which afford the advantages of [[multiplexing]] multiple concurrent [[Session (computer science)|communication session]]s. ''Telecommunication'' is often used in its plural form.

Other examples of pre-modern long-distance communication included audio messages, such as coded [[drum (communication)|drumbeats]], lung-blown [[Horn (instrument)|horns]], and loud [[whistle]]s. 20th- and 21st-century technologies for long-distance communication usually involve electrical and electromagnetic technologies, such as [[electrical telegraph|telegraph]], [[telephone]], television and [[teleprinter]], [[telecommunication network|networks]], radio, [[microwave transmission]], [[Fiber-optic communication|optical fiber]], and [[communications satellite]]s.

A revolution in [[wireless communication]] began in the first decade of the 20th century with the pioneering developments in [[radio communications]] by [[Guglielmo Marconi]], who won the [[Nobel Prize in Physics]] in 1909, and other notable pioneering inventors and developers in the field of electrical and electronic telecommunications. These included [[Charles Wheatstone]] and [[Samuel F.B. Morse|Samuel Morse]] (inventors of the telegraph), [[Antonio Meucci]] and [[Alexander Graham Bell]] (some of the inventors and developers of the telephone, see [[Invention of the telephone]]), [[Edwin Armstrong]] and [[Lee de Forest]] (inventors of radio), as well as [[Vladimir K. Zworykin]], [[John Logie Baird]] and [[Philo Farnsworth]] (some of the inventors of television).

The early telecommunication networks were created with copper wires as the physical medium for signal transmission. For many years, these networks were used for basic phone services, namely voice and telegrams. Since the mid-1990s, as the internet has grown in popularity, voice has been gradually supplanted by data. This soon demonstrated the limitations of copper in data transmission, prompting the development of optics.<ref name=":11">{{Cite web|title=How does a Gigabit Passive Optical Network (GPON) work?|url=https://www.eib.org/en/stories/what-is-gpon|access-date=7 June 2021|website=European Investment Bank|language=en|archive-date=7 June 2021|archive-url=https://web.archive.org/web/20210607144149/https://www.eib.org/en/stories/what-is-gpon|url-status=live}}</ref><ref>{{Cite book|url=https://www.nap.edu/read/11711/chapter/3|title=Read "Renewing U.S. Telecommunications Research" at NAP.edu|year=2006|doi=10.17226/11711|isbn=978-0-309-10265-0|language=en|access-date=25 June 2021|archive-date=23 June 2021|archive-url=https://web.archive.org/web/20210623221636/https://www.nap.edu/read/11711/chapter/3|url-status=live}}</ref><ref>{{Cite web|last=Cyphers|first=Bennett|title=The Case for Fiber to the Home, Today: Why Fiber is a Superior Medium for 21st Century Broadband|url=https://www.eff.org/wp/case-fiber-home-today-why-fiber-superior-medium-21st-century-broadband|access-date=7 June 2021|website=Electronic Frontier Foundation|language=en|archive-date=3 June 2021|archive-url=https://web.archive.org/web/20210603233817/https://www.eff.org/wp/case-fiber-home-today-why-fiber-superior-medium-21st-century-broadband|url-status=live}}</ref>

== Etymology ==
''Telecommunication'' is a compound noun of the Greek prefix ''tele-'' (τῆλε), meaning ''distant'', ''far off'', or ''afar'',<ref>{{cite web|url=http://www.etymonline.com/index.php?term=tele-&allowed_in_frame=0|title=Online Etymology Dictionary|access-date=19 August 2016|archive-date=25 December 2016|archive-url=https://web.archive.org/web/20161225225345/http://www.etymonline.com/index.php?term=tele-&allowed_in_frame=0|url-status=live}}</ref> and the Latin verb ''communicare'', meaning ''to share''. Its modern use is adapted from the French,<ref name="oxford">{{cite web |url=http://oxforddictionaries.com/definition/english/telecommunication?view=uk |title=Telecommunication |work=Oxford Dictionaries |publisher=Oxford University Press |access-date=28 February 2013 |archive-date=30 April 2013 |archive-url=https://web.archive.org/web/20130430020541/http://oxforddictionaries.com/definition/english/telecommunication?view=uk |url-status=dead }}</ref> because its written use was recorded in 1904 by the French engineer and novelist [[Édouard Estaunié]].<ref>{{cite web|first=Jean-Marie|last=Dilhac|url=http://www.ieee.org/portal/cms_docs_iportals/iportals/aboutus/history_center/conferences/che2004/Dilhac.pdf|title=From tele-communicare to Telecommunications|website=[[Institute of Electrical and Electronics Engineers]] (IEEE) |archive-url=https://web.archive.org/web/20101202232403/http://www.ieee.org/portal/cms_docs_iportals/iportals/aboutus/history_center/conferences/che2004/Dilhac.pdf |archive-date=2 December 2010|year=2004}}</ref><ref>''Telecommunication'', ''tele-'' and ''communication'', [[New Oxford American Dictionary]] (2nd edition), 2005.</ref> ''Communication'' was first used as an English word in the late 14th century. It comes from Old French comunicacion (14c., Modern French communication), from Latin communicationem (nominative communication), noun of action from past participle stem of communicare, "to share, divide out; communicate, impart, inform; join, unite, participate in," literally, "to make common," from communis."<ref>{{cite web|url=http://www.etymonline.com/index.php?term=communication&allowed_in_frame=0|title=Online Etymology Dictionary|access-date=19 August 2016|archive-date=14 September 2016|archive-url=https://web.archive.org/web/20160914041535/http://www.etymonline.com/index.php?term=communication&allowed_in_frame=0|url-status=live}}</ref>

== History ==
{{further|History of telecommunication}}

At the 1932 [[ITU Plenipotentiary Conference|Plenipotentiary Telegraph Conference]] and the International Radiotelegraph Conference in Madrid, the two organizations decided to merge to form the [[International Telecommunication Union]] (ITU).<ref>{{cite web|url=https://www.itu.int/en/history/Pages/PlenipotentiaryConferences.aspx?conf=4.5|title=International Telegraph Conference (Madrid, 1932)|publisher=ITU|access-date=8 January 2023|archive-date=8 January 2023|archive-url=https://web.archive.org/web/20230108011921/https://www.itu.int/en/history/Pages/PlenipotentiaryConferences.aspx?conf=4.5|url-status=live}}</ref> They defined ''telecommunication'' as "any telegraphic or telephonic communication of signs, signals, writing, facsimiles and sounds of any kind, by wire, wireless or other systems or processes of electric signaling or visual signaling (semaphores)."

The definition was later reconfirmed, according to Article 1.3 of the [[ITU Radio Regulations|Radio Regulations]] (RR), telecommunication, which defined it as "Any [[Transmission (telecommunications)|transmission]], [[Emission (radiocommunications)|emission]] or reception of signs, signals, writings, images and sounds or intelligence of any nature by [[wire]], radio, optical, or other [[electromagnetic]] systems".

=== Beacons and pigeons ===
[[File:OptischerTelegraf.jpg|upright|thumb|A replica of one of [[Claude Chappe|Chappe's]] [[semaphore tower]]s]]

[[Homing pigeon]]s have been used throughout history by different cultures. [[Pigeon post]] had [[Persia]]n roots and was later used by the Romans to aid their military. [[Frontinus]] claimed [[Julius Caesar]] used pigeons as messengers in his conquest of [[Gaul]].<ref name = "Levi">{{cite book |last=Levi |first=Wendell |title= The Pigeon|year= 1977|publisher= Levi Publishing Co, Inc|location= Sumter, SC|isbn=978-0-85390-013-9 }}</ref>
The [[Greeks]] also conveyed the names of the victors at the [[Ancient Olympic Games|Olympic Games]] to various cities using homing pigeons.<ref>{{cite book | last =Blechman | first =Andrew | title =Pigeons-The fascinating saga of the world's most revered and reviled bird. | publisher =University of Queensland Press | year =2007 | location =St Lucia, Queensland | url =http://www.uqp.uq.edu.au/book_details.php?id=9780702236419 | isbn =978-0-7022-3641-9 | url-status=dead | archive-url =https://web.archive.org/web/20080514003720/http://www.uqp.uq.edu.au/book_details.php?id=9780702236419 | archive-date =14 May 2008 | df =dmy-all }}</ref> In the early 19th century, the Dutch government used the system in [[Java (island)|Java]] and [[Sumatra]]. And in 1849, [[Paul Julius Reuter]] started a pigeon service to fly stock prices between [[Aachen]] and [[Brussels]], a service that operated for a year until the gap in the telegraph link was closed.<ref>{{cite news| title =Chronology: Reuters, from pigeons to multimedia merger| newspaper =Reuters| url =https://www.reuters.com/article/rbssTechMediaTelecomNews/idUSL1849100620080219| format =Web article| access-date =21 February 2008| date =19 February 2008| archive-date =26 March 2008| archive-url =https://web.archive.org/web/20080326192232/http://www.reuters.com/article/rbssTechMediaTelecomNews/idUSL1849100620080219| url-status =live}}</ref>

In the Middle Ages, chains of [[beacon]]s were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use was during the [[Spanish Armada]], when a beacon chain relayed a signal from [[Plymouth]] to [[London]].<ref>{{cite web|first=David|last=Ross|url=http://www.britainexpress.com/History/tudor/armada.htm|title=The Spanish Armada|archive-url=https://web.archive.org/web/20200104142345/https://www.britainexpress.com/History/tudor/armada.htm|archive-date=4 January 2020|website=Britain Express|access-date=October 1, 2007}}</ref>

In 1792, [[Claude Chappe]], a French engineer, built the first fixed visual [[telegraphy]] system (or [[semaphore line]]) between [[Lille]] and Paris.<ref>{{cite web|url=http://chappe.ec-lyon.fr/|archive-url=https://web.archive.org/web/20040409014107/http://chappe.ec-lyon.fr/|title=Les Télégraphes Chappe|archive-date=2004-04-09|website=Cédrick Chatenet|location=l'Ecole Centrale de Lyon|year=2003}}</ref> However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres (six to nineteen miles). As a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880.<ref>{{cite web|url=http://www.itu.int/itudoc/gs/promo/tsb/88192.pdf|title=CCIT/ITU-T 50 Years of Excellence|archive-url=https://web.archive.org/web/20200212173522/https://www.itu.int/itudoc/gs/promo/tsb/88192.pdf|archive-date=12 February 2020|website=International Telecommunication Union|year=2006}}</ref>

=== Telegraph and telephone ===
On July 25, 1837, the first commercial [[electrical telegraph]] was demonstrated by English inventor Sir [[William Fothergill Cooke]] and English scientist Sir [[Charles Wheatstone]].<ref>{{cite book|first=William|last=Brockedone|title=Cooke and Wheatstone and the Invention of the Electric Telegraph|isbn=9780415846783}}</ref><ref>{{Cite news|url=https://www.telegraph.co.uk/technology/connecting-britain/first-electric-telegraph/|title=Who made the first electric telegraph communications?|work=The Telegraph|access-date=7 August 2017|language=en-GB|archive-date=8 August 2017|archive-url=https://web.archive.org/web/20170808003926/http://www.telegraph.co.uk/technology/connecting-britain/first-electric-telegraph/|url-status=live}}</ref> Both inventors viewed their device as "an improvement to the [existing] electromagnetic telegraph" and not as a new device.<ref>{{cite web|url=https://www.du.edu/~jcalvert/tel/morse/morse.htm|archive-url=https://web.archive.org/web/20010616184336/https://www.du.edu/~jcalvert/tel/morse/morse.htm|archive-date=2001-06-16|title=The Electromagnetic Telegraph|first=J. B.|last=Calvert}}</ref>

[[Samuel Morse]] independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on September 2, 1837. [[Morse code|His code]] was an important advance over Wheatstone's signaling method. The first [[transatlantic telegraph cable]] was successfully completed on July 27, 1866, allowing transatlantic telecommunication for the first time.<ref>{{cite web|url=http://www.sil.si.edu/digitalcollections/hst/atlantic-cable/|title=The Atlantic Cable|archive-url=https://web.archive.org/web/20170701144122/http://www.sil.si.edu/digitalcollections/hst/atlantic-cable/|archive-date=1 July 2017|website=Bern Dibner|publisher=Burndy Library Inc.|year=1959}}</ref>

The conventional telephone was patented by [[Alexander Graham Bell|Alexander Bell]] in 1876. [[Elisha Gray]] also filed a caveat for it in 1876. Gray abandoned his caveat and because he did not contest Bell's priority, the examiner approved Bell's patent on March 3, 1876. Gray had filed his caveat for the variable resistance telephone, but Bell was the first to document the idea and test it in a telephone.[88]<ref>{{cite web|url=http://www.oberlin.edu/external/EOG/OYTT-images/ElishaGray.html|title=Elisha Gray|archive-url=https://web.archive.org/web/20170628164416/http://www2.oberlin.edu/external/EOG/OYTT-images/ElishaGray.html|archive-date=28 June 2017|website=Oberlin College Archives|publisher=Electronic Oberlin Group|year=2006}}</ref> [[Antonio Meucci]] invented a device that allowed the electrical transmission of voice over a line nearly 30 years before in 1849, but his device was of little practical value because it relied on the [[electrophonic effect]] requiring users to place the receiver in their mouths to "hear."<ref>{{cite web|url=http://chem.ch.huji.ac.il/~eugeniik/history/meucci.html|archive-url=https://web.archive.org/web/20060424055029/http://chem.ch.huji.ac.il/~eugeniik/history/meucci.html|archive-date=2006-04-24|title=Antonio Santi Giuseppe Meucci|first=Eugenii|last=Katz}}</ref> The first commercial telephone services were set up by the Bell Telephone Company in 1878 and 1879 on both sides of the Atlantic in the cities of [[New Haven]] and London.<ref>{{cite web|url=http://www.connected-earth.com/Galleries/Telecommunicationsage/Thetelephone/index.htm|title=Connected Earth: The telephone|archive-url=https://web.archive.org/web/20060822104544/http://www.connected-earth.com/Galleries/Telecommunicationsage/Thetelephone/index.htm|archive-date=22 August 2006|publisher=BT|year=2006}}</ref><ref>{{cite web|url=https://www.att.com/history/milestones.html|archive-url=https://web.archive.org/web/20030114033744/https://www.att.com/history/milestones.html|title=History of AT&T|archive-date=2003-01-14|website=AT&T}}</ref>

=== Radio and television ===
In 1894, Italian inventor [[Guglielmo Marconi]] began developing a wireless communication using the then-newly discovered phenomenon of [[radio wave]]s, showing by 1901 that they could be transmitted across the Atlantic Ocean.<ref>{{cite web|url=http://www.teslasociety.com/biography.htm|title=Tesla Biography|archive-url=https://web.archive.org/web/20160114205727/http://www.teslasociety.com/biography.htm |archive-date=14 January 2016|first=Ljubo|last=Vujovic|website=Tesla Memorial Society of New York|year=1998}}</ref> This was the start of [[wireless telegraphy]] by radio. On 17 December 1902, a transmission from the Marconi station in [[Glace Bay]], Nova Scotia, Canada, became the world's first radio message to cross the Atlantic from North America. In 1904, a commercial service was established to transmit nightly news summaries to subscribing ships, which incorporated them into their onboard newspapers.<ref>{{Cite web|title=TR Center - Talking Across the Ocean|url=https://www.theodorerooseveltcenter.org/Blog/Item/Talking%20Across%20the%20Ocean|access-date=2021-03-12|website=www.theodorerooseveltcenter.org|archive-date=17 April 2021|archive-url=https://web.archive.org/web/20210417162827/https://www.theodorerooseveltcenter.org/Blog/Item/Talking%20Across%20the%20Ocean|url-status=live}}</ref>

[[World War I]] accelerated the development of radio for [[military communications]]. After the war, commercial radio [[AM broadcasting]] began in the 1920s and became an important mass medium for entertainment and news. [[World War II]] again accelerated the development of radio for the wartime purposes of aircraft and land communication, radio navigation, and radar.<ref>{{cite book|isbn=9781118104644|last=Thompson|first=R.J. Jr.|year=2011|title=Crystal Clear: The Struggle for Reliable Communications Technology in World War II|location=Hoboken, NJ|publisher=Wiley}}</ref> Development of stereo [[FM broadcasting]] of radio began in the 1930s in the United States and the 1970s in the United Kingdom, displacing AM as the dominant commercial standard.<ref>{{cite book|isbn=9781623566654|last1=Théberge|first1=P.|last2=Devine|first2=K.|last3=Everrett|first3=T|year=2015|title=Living Stereo: Histories and Cultures of Multichannel Sound|location=New York|publisher=Bloomsbury Publishing}}</ref>

On March 25, 1925, [[John Logie Baird]] demonstrated the transmission of moving pictures at the London department store [[Selfridges]]. Baird's device relied upon the [[Nipkow disk]] and thus became known as the [[mechanical television]]. It formed the basis of experimental broadcasts done by the [[British Broadcasting Corporation]] beginning on 30 September 1929.<ref>{{cite web|url=http://www.mztv.com/newframe.asp?content=http://www.mztv.com/pioneers.html|title=The Pioneers|archive-url=https://web.archive.org/web/20130514070220/http://www.mztv.com/newframe.asp?content=http%3A%2F%2Fwww.mztv.com%2Fpioneers.html|archive-date=14 May 2013|website=MZTV Museum of Television|year=2006}}</ref> However, for most of the 20th century, televisions depended on the [[cathode ray tube]] invented by [[Karl Ferdinand Braun|Karl Braun]]. The first version of such a television to show promise was produced by [[Philo Farnsworth]] and demonstrated to his family on 7 September 1927.<ref>{{cite web|url=http://www.time.com/time/time100/scientist/profile/farnsworth.html|title=Philo Farnsworth|archive-url=https://web.archive.org/web/20090930214902/http://www.time.com/time/time100/scientist/profile/farnsworth.html |archive-date=30 September 2009|first=Neil|last=Postman|website=[[TIME Magazine]]}}</ref> After [[World War II]], interrupted experiments resumed and television became an important home entertainment broadcast medium.

=== Thermionic valves ===
The type of device known as a ''[[thermionic tube]]'' or ''thermionic valve'' uses [[thermionic emission]] of electrons from a [[hot cathode|heated cathode]] for a number of fundamental electronic functions such as signal [[amplifier|amplification]] and current [[rectifier|rectification]].

The simplest vacuum tube, the [[diode]] invented in 1904 by [[John Ambrose Fleming]], contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to the anode. Adding one or more [[control grid]]s within the tube enables the current between the cathode and anode to be controlled by the voltage on the grid or grids.<ref>{{cite web|last=Hoddeson|first=L|title=The Vacuum Tube|url=https://www.pbs.org/transistor/science/events/vacuumt.html|publisher=PBS|access-date=6 May 2012|url-status=live|archive-url=https://web.archive.org/web/20120415063342/http://www.pbs.org/transistor/science/events/vacuumt.html|archive-date=15 April 2012}}</ref> These devices became a key component of electronic circuits for the first half of the 20th century and were crucial to the development of radio, television, radar, [[sound recording and reproduction]], long-distance telephone networks, and analogue and early digital [[computers]]. While some applications had used earlier technologies such as the [[spark gap transmitter]] for radio or [[mechanical computer]]s for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, leading to the creation of [[electronics]].<ref>{{cite book |last1=Macksey |first1=Kenneth |last2=Woodhouse |first2=William |year=1991 |chapter=Electronics |title=The Penguin Encyclopedia of Modern Warfare: 1850 to the present day |publisher=Viking |page=110 |isbn=978-0-670-82698-8 |quote=The electronics age may be said to have been ushered in with the invention of the vacuum diode valve in 1902 by the Briton John Fleming (himself coining the word 'electronics'), the immediate application being in the field of radio.}}</ref>

In the 1940s, the invention of [[semiconductor devices]] made it possible to produce [[Solid state electronics|solid-state]] devices, which are smaller, cheaper, and more efficient, reliable, and durable than thermionic tubes. Starting in the mid-1960s, thermionic tubes were replaced with the [[transistor]]. Thermionic tubes still have some applications for certain high-frequency amplifiers.

==== Computer networks and the Internet ====
On 11 September 1940, [[George Stibitz]] transmitted problems for his Complex Number Calculator in New York using a [[Teleprinter|teletype]] and received the computed results back at [[Dartmouth College]] in [[New Hampshire]].<ref>{{Cite web|title=George Stibitz (1904–1995)|url=http://www.kerryr.net/pioneers/stibitz.htm|access-date=6 June 2023|website=www.kerryr.net|publisher=Kerry Redshaw|archive-date=15 August 2017|archive-url=https://web.archive.org/web/20170815235330/http://www.kerryr.net/pioneers/stibitz.htm|url-status=live}}</ref> This configuration of a centralized computer ([[Mainframe computer|mainframe]]) with remote [[dumb terminals]] remained popular well into the 1970s. In the 1960s, researchers started to investigate [[packet switching]], a technology that sends a message in portions to its destination [[Asynchronous Transfer Mode|asynchronously]] without passing it through a centralized [[mainframe]]. A four-[[node (networking)|node]] [[computer network|network]] emerged on 5 December 1969, constituting the beginnings of the [[ARPANET]], which by 1981 had grown to 213 nodes.<ref>{{cite book | last = Hafner | first = Katie | title = Where Wizards Stay Up Late: The Origins Of The Internet | publisher = Simon & Schuster | year = 1998 | isbn = 978-0-684-83267-8 }}</ref> ARPANET eventually merged with other networks to form the Internet. While Internet development was a focus of the [[Internet Engineering Task Force]] (IETF) who published a series of [[Request for Comments]] documents, other networking advancements occurred in [[industrial laboratory|industrial laboratories]], such as the [[local area network]] (LAN) developments of [[Ethernet]] (1983) and [[Token Ring]] (1984){{citation needed}}.

=== Growth of transmission capacity ===
The effective capacity to exchange information worldwide through two-way telecommunication networks grew from 281 [[petabytes]] (pB) of optimally compressed information in 1986 to 471 pB in 1993 to 2.2 [[exabytes]] (eB) in 2000 to 65 eB in 2007.<ref name="HilbertLopez2011">{{cite journal|url=https://www.science.org/doi/10.1126/science.1200970|title=The World's Technological Capacity to Store, Communicate, and Compute Information|archive-url=https://web.archive.org/web/20130727161911/http://www.sciencemag.org/content/332/6025/60 |archive-date=27 July 2013|first1=Martin|last1=Hilbert|first2=Priscila|last2=López|year=2011|journal=[[Science (journal)|Science]]|volume=332|issue=6025|pages=60–65|doi=10.1126/science.1200970|pmid=21310967|bibcode=2011Sci...332...60H|s2cid=206531385}}</ref> This is the informational equivalent of two newspaper pages per person per day in 1986, and six entire newspapers per person per day by 2007.<ref>{{cite news|url=http://ideas.economist.com/video/giant-sifting-sound-0|title=video animation|newspaper=The Economist|archive-url=https://web.archive.org/web/20120118072720/http://ideas.economist.com/video/giant-sifting-sound-0 |archive-date=18 January 2012}}</ref> Given this growth, telecommunications play an increasingly important role in the world economy and the global telecommunications industry was about a $4.7 trillion sector in 2012.<ref name="plunkettresearch01">{{cite web|url=http://www.plunkettresearch.com/Telecommunications/TelecommunicationsStatistics/tabid/96/Default.aspx|title=Worldwide Telecommunications Industry Revenues|archive-url=https://web.archive.org/web/20100328045302/http://www.plunkettresearch.com/Telecommunications/TelecommunicationsStatistics/tabid/96/Default.aspx |archive-date=28 March 2010|website=Plunkett's Telecommunications Industry Almanac 2010}}</ref><ref name="plunkettresearch02">{{Cite web |title=Introduction to the Telecommunications Industry |url=http://www.plunkettresearch.com/telecommunications-market-research/industry-and-business-data/statistics |website=Plunkett Research |archive-url=https://web.archive.org/web/20121022031016/http://www.plunkettresearch.com/telecommunications-market-research/industry-and-business-data/statistics |archive-date=22 October 2012}}</ref> The service revenue of the global telecommunications industry was estimated to be $1.5 trillion in 2010, corresponding to 2.4% of the world's gross domestic product (GDP).<ref name="plunkettresearch01" />

== Technical concepts ==
Modern telecommunication is founded on a series of key concepts that experienced progressive development and refinement in a period of well over a century:

=== Basic elements ===
Telecommunication technologies may primarily be divided into wired and wireless methods. Overall, a basic telecommunication system consists of three main parts that are always present in some form or another:
* A [[transmitter]] that takes information and converts it to a [[signal (electrical engineering)|signal]]
* A [[transmission medium]], also called the ''physical channel,'' that carries the signal (e.g. the [[Free-space optical communication|"free space channel")]]
* A [[receiver (radio)|receiver]] that takes the signal from the channel and converts it back into usable information for the recipient

In a [[radio station|radio broadcasting station]], the station's large [[power amplifier]] is the transmitter and the broadcasting [[antenna (radio)|antenna]] is the interface between the power amplifier and the free space channel. The free space channel is the transmission medium and the receiver's antenna is the interface between the free space channel and the receiver. Next, the [[radio receiver]] is the destination of the radio signal, where it is converted from electricity to sound.

Telecommunication systems are occasionally [[duplex (telecommunications)|"duplex"]] (two-way systems) with a single box of [[electronics]] working as both the transmitter and a receiver, or a ''transceiver'' (e.g., a [[mobile phone]]).<ref name="stallings-intro">{{cite book | last = Haykin | first = Simon | edition= 4th | title = Communication Systems | url = https://archive.org/details/communicationsy000simo | url-access = registration | publisher = John Wiley & Sons | year = 2001 | pages = [https://archive.org/details/communicationsy000simo/page/n21 1]–3 | isbn = 978-0-471-17869-9 }}</ref> The transmission electronics and the receiver electronics within a transceiver are quite independent of one another. This can be explained by the fact that radio transmitters contain power amplifiers that operate with electrical powers measured in watts or kilowatts, but radio receivers deal with radio powers measured in microwatts or [[nanowatt]]s. Hence, transceivers have to be carefully designed and built to isolate their high-power circuitry and their low-power circuitry from each other to avoid interference.

Telecommunication over fixed lines is called [[point-to-point communication]] because it occurs between a transmitter and a receiver. Telecommunication through radio broadcasts is called [[broadcasting|broadcast communication]] because it occurs between a powerful transmitter and numerous low-power but sensitive radio receivers.<ref name="stallings-intro" />

Telecommunications in which multiple transmitters and multiple receivers have been designed to cooperate and share the same physical channel are called [[multiplexing|multiplex systems]]. The sharing of physical channels using multiplexing often results in significant cost reduction. Multiplexed systems are laid out in telecommunication networks and multiplexed signals are switched at nodes through to the correct destination terminal receiver.

=== Analog versus digital communications ===
Communications signals can be sent by [[analog signal]]s or [[Digital signal (electronics)|digital signals]] via [[analog communication]] systems or [[digital communication]] systems. Analog signals vary continuously with respect to the information, while digital signals encode information as a set of discrete values (e.g., a set of ones and zeroes).<ref name=Ambardar>{{cite book | last = Ambardar | first = Ashok | edition = 2nd | title = Analog and Digital Signal Processing | publisher = Brooks/Cole Publishing Company | year = 1999 | pages = [https://archive.org/details/analogdigitalsig00amba/page/1 1–2] | isbn = 978-0-534-95409-3 | url-access = registration | url = https://archive.org/details/analogdigitalsig00amba/page/1 }}</ref> During propagation and reception, information contained in analog signals is degraded by [[noise (signal processing)|undesirable physical noise]]. Commonly, the noise in a communication system can be expressed as adding or subtracting from the desirable signal in a [[random process|random way]]. This form of noise is called [[additive noise]], with the understanding that the noise can be negative or positive at different instances.

Unless the additive noise disturbance exceeds a certain threshold, the information contained in digital signals will remain intact. Their resistance to noise represents a key advantage of digital signals over analog signals. However, digital systems [[Cliff effect|fail catastrophically]] when noise exceeds the system's ability to autocorrect. On the other hand, analog systems fail gracefully: as noise increases, the signal becomes progressively more degraded but still usable. Also, digital transmission of [[continuous signal|continuous data]] unavoidably adds [[quantization noise]] to the output. This can be reduced, but not eliminated, only at the expense of increasing the channel bandwidth requirement.

=== Communication channels ===
The term "channel" has two different meanings. In one meaning, a channel is the physical medium that carries a signal between the transmitter and the receiver. Examples of this include the [[atmosphere]] for sound communications, glass [[optical fiber]]s for some kinds of [[optical communications]], [[coaxial cable]]s for communications by way of the voltages and electric currents in them, and [[Free-space optical communication|free space]] for communications using [[visible light]], [[infrared]] waves, [[ultraviolet light]], and [[radio wave]]s. Coaxial cable types are classified by RG type or "radio guide", terminology derived from World War II. The various RG designations are used to classify the specific signal transmission applications.<ref>{{Cite news|url=http://www.conwire.com/coax-cable-rg-cable-blog|title=Coax Cable FAQ Series: What is RG Cable? – Conwire|work=Conwire|access-date=7 August 2017|language=en-US|archive-date=8 August 2017|archive-url=https://web.archive.org/web/20170808000629/http://www.conwire.com/coax-cable-rg-cable-blog|url-status=live}}</ref> This last channel is called the "free space channel". The sending of radio waves from one place to another has nothing to do with the presence or absence of an atmosphere between the two. Radio waves travel through a perfect [[vacuum]] just as easily as they travel through air, fog, clouds, or any other kind of gas.

The other meaning of the term "channel" in telecommunications is seen in the phrase [[channel (communications)|communications channel]], which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in the neighborhood of 94.5 [[MHz]] (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighborhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency [[bandwidth (signal processing)|bandwidth]] of about 180 [[kHz]] (kilohertz), centered at frequencies such as the above, which are called the [[Carrier wave|"carrier frequencies"]]. Each station in this example is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system.

In the example above, the "free space channel" has been divided into communications channels according to [[frequency|frequencies]], and each channel is assigned a separate frequency bandwidth in which to broadcast radio waves. This system of dividing the medium into channels according to frequency is called "[[frequency-division multiplexing]]". Another term for the same concept is "[[wavelength-division multiplexing]]", which is more commonly used in optical communications when multiple transmitters share the same physical medium.

Another way of dividing a communications medium into channels is to allocate each sender a recurring segment of time (a "time slot", for example, 20 [[milliseconds]] out of each second), and to allow each sender to send messages only within its own time slot. This method of dividing the medium into communication channels is called "[[time-division multiplexing]]" ('''TDM'''), and is used in optical fibre communication. Some radio communication systems use TDM within an allocated FDM channel. Hence, these systems use a hybrid of TDM and FDM.

=== Modulation ===
The shaping of a signal to convey information is known as [[modulation]]. Modulation can be used to represent a digital message as an analog waveform. This is commonly called [[keying (telecommunications)|"keying"]]—a term derived from the older use of Morse Code in telecommunications—and several keying techniques exist (these include [[phase-shift keying]], [[frequency-shift keying]], and [[amplitude-shift keying]]). The "[[Bluetooth]]" system, for example, uses phase-shift keying to exchange information between various devices.<ref>Haykin, pp. 344–403.</ref><ref>[http://www.bluetooth.org/foundry/adopters/document/Core_v2.0_EDR/en/1/Core_v2.0_EDR.zip Bluetooth Specification Version 2.0 + EDR] {{Webarchive|url=https://web.archive.org/web/20140814042933/https://www.bluetooth.org/foundry/adopters/document/Core_v2.0_EDR/en/1/Core_v2.0_EDR.zip }} (p. 27), Bluetooth, 2004.</ref> In addition, there are combinations of phase-shift keying and amplitude-shift keying which is called (in the jargon of the field) "[[quadrature amplitude modulation]]" (QAM) that are used in high-capacity digital radio communication systems.

Modulation can also be used to transmit the information of low-frequency analog signals at higher frequencies. This is helpful because low-frequency analog signals cannot be effectively transmitted over free space. Hence the information from a low-frequency analog signal must be impressed into a higher-frequency signal (known as the "[[carrier wave]]") before transmission. There are several different modulation schemes available to achieve this [two of the most basic being [[amplitude modulation]] (AM) and [[frequency modulation]] (FM)]. An example of this process is a disc jockey's voice being impressed into a 96 MHz carrier wave using frequency modulation (the voice would then be received on a radio as the channel "96 FM").<ref>Haykin, pp. 88–126.</ref> In addition, modulation has the advantage that it may use frequency division multiplexing (FDM).

=== Telecommunication networks ===
A [[telecommunications network]] is a collection of transmitters, receivers, and [[communications channel]]s that send messages to one another. Some digital communications networks contain one or more [[Router (computing)|routers]] that work together to transmit information to the correct user. An analog communications network consists of one or more [[telephone switch|switches]] that establish a connection between two or more users. For both types of networks, [[repeater]]s may be necessary to amplify or recreate the signal when it is being transmitted over long distances. This is to combat [[attenuation]] that can render the signal indistinguishable from the noise.<ref name="glossary">[http://www.atis.org/tg2k/ ATIS Telecom Glossary 2000] {{webarchive|url=https://web.archive.org/web/20080302071329/http://www.atis.org/tg2k/ }}, ATIS Committee T1A1 Performance and Signal Processing (approved by the American National Standards Institute), 28 February 2001.</ref>
Another advantage of digital systems over analog is that their output is easier to store in memory, i.e. two voltage states (high and low) are easier to store than a continuous range of states.

== Societal impact ==
Telecommunication has a significant social, cultural and economic impact on modern society. In 2008, estimates placed the [[telecommunication industry]]'s revenue at US$4.7 trillion or just under three percent of the [[gross world product]] (official exchange rate).<ref name="plunkettresearch01" /> Several following sections discuss the impact of telecommunication on society.

=== Microeconomics ===
On the [[Microeconomics|microeconomic]] scale, companies have used telecommunications to help build global business empires. This is self-evident in the case of online retailer [[Amazon.com]] but, according to academic Edward Lenert, even the conventional retailer [[Walmart]] has benefited from better telecommunication infrastructure compared to its competitors.<ref>{{cite journal | last = Lenert | first = Edward | title = A Communication Theory Perspective on Telecommunications Policy | journal = Journal of Communication| volume = 48 | issue = 4 | pages = 3–23 |doi=10.1111/j.1460-2466.1998.tb02767.x}}</ref> In cities throughout the world, home owners use their telephones to order and arrange a variety of home services ranging from pizza deliveries to electricians. Even relatively poor communities have been noted to use telecommunication to their advantage. In [[Bangladesh]]'s [[Narsingdi District]], isolated villagers use cellular phones to speak directly to wholesalers and arrange a better price for their goods. In [[Ivory Coast|Côte d'Ivoire]], coffee growers share mobile phones to follow hourly variations in coffee prices and sell at the best price.<ref>{{cite thesis | author = Mireille Samaan | title = The Effect of Income Inequality on Mobile Phone Penetration | publisher = Boston University |type = Honors thesis | date = April 2003 | url = http://dissertations.bc.edu/cgi/viewcontent.cgi?article=1016&context=ashonors | format = PDF | access-date =8 June 2007 |archive-url = https://web.archive.org/web/20070214102055/http://dissertations.bc.edu/cgi/viewcontent.cgi?article=1016&context=ashonors |archive-date = 14 February 2007}}</ref>

=== Macroeconomics ===
On the [[Macroeconomics|macroeconomic]] scale, Lars-Hendrik Röller and [[Leonard Waverman]] suggested a causal link between good telecommunication infrastructure and economic growth.<ref>{{cite journal | doi = 10.1257/aer.91.4.909 | last = Röller | first = Lars-Hendrik |author2=Leonard Waverman | title = Telecommunications Infrastructure and Economic Development: A Simultaneous Approach | journal = American Economic Review | issn = 0002-8282 | year = 2001 | volume = 91 | issue = 4 | pages = 909–23| citeseerx = 10.1.1.202.9393 }}</ref><ref>{{cite web |author1=Christine Zhen-Wei Qiang and Carlo M. Rossotto with Kaoru Kimura |title=Economic Impacts of Broadband |url=http://siteresources.worldbank.org/EXTIC4D/Resources/IC4D_Broadband_35_50.pdf |website=siteresources.worldbank.org |access-date=31 March 2016 |archive-date=12 August 2020 |archive-url=https://web.archive.org/web/20200812035517/http://message.worldbank.org/isp_error_page.htm |url-status=live }}</ref> Few dispute the existence of a correlation although some argue it is wrong to view the relationship as causal.<ref>{{cite journal | last = Riaz | first = Ali | title = The role of telecommunications in economic growth: proposal for an alternative framework of analysis | journal = Media, Culture & Society | year = 1997 | volume = 19 | issue = 4 | pages = 557–83 | doi = 10.1177/016344397019004004| s2cid = 154398428 }}</ref>

Because of the economic benefits of good telecommunication infrastructure, there is increasing worry about the inequitable access to telecommunication services amongst various countries of the world—this is known as the [[digital divide]]. A 2003 survey by the [[International Telecommunication Union]] (ITU) revealed that roughly a third of countries have fewer than one mobile subscription for every 20 people and one-third of countries have fewer than one land-line telephone subscription for every 20 people. In terms of Internet access, roughly half of all countries have fewer than one out of 20 people with Internet access. From this information, as well as educational data, the ITU was able to compile an index that measures the overall ability of citizens to access and use information and communication technologies.<ref>{{cite web|title=Digital Access Index (DAI)|url=http://www.itu.int/ITU-D/ict/dai/|publisher=itu.int|access-date=6 March 2008|archive-date=2 January 2019|archive-url=https://web.archive.org/web/20190102061041/http://www.itu.int/ITU-D/ict/dai/|url-status=live}}</ref> Using this measure, Sweden, Denmark and [[Iceland]] received the highest ranking while the African countries [[Niger]], [[Burkina Faso]] and [[Mali]] received the lowest.<ref>{{Cite web |title=World Telecommunication Development Report 2003: Access Indicators for the Information Society: Executive Summary |url=https://www.itu.int/ITU-D/ict/publications/wtdr_03/material/WTDR2003Sum_e.pdf |website=International Telecommunication Union (ITU) |page=22 |access-date=6 June 2023 |archive-date=6 June 2023 |archive-url=https://web.archive.org/web/20230606100635/https://www.itu.int/ITU-D/ict/publications/wtdr_03/material/WTDR2003Sum_e.pdf |url-status=live }}</ref>

=== Social impact ===
Telecommunication has played a significant role in social relationships. Nevertheless, devices like the telephone system were originally advertised with an emphasis on the practical dimensions of the device (such as the ability to conduct business or order home services) as opposed to the social dimensions. It was not until the late 1920s and 1930s that the social dimensions of the device became a prominent theme in telephone advertisements. New promotions started appealing to consumers' emotions, stressing the importance of social conversations and staying connected to family and friends.<ref name="fischer">Fischer, Claude S. {{"'}}Touch Someone': The Telephone Industry Discovers Sociability." Technology and Culture 29.1 (January 1988): 32–61. {{doi|10.2307/3105226}}. {{JSTOR|3105226}}.</ref>

Since then the role that telecommunications has played in social relations has become increasingly important. In recent years,{{Since when}} the popularity of [[social networking site]]s has increased dramatically. These sites allow users to communicate with each other as well as post photographs, events and profiles for others to see. The profiles can list a person's age, interests, sexual preference and relationship status. In this way, these sites can play important role in everything from organising social engagements to [[courtship]].<ref>{{cite news|title=How do you know your love is real? Check Facebook|publisher=CNN|url=http://www.cnn.com/2008/LIVING/personal/04/04/facebook.love/index.html|access-date=8 February 2009|archive-date=6 November 2017|archive-url=https://web.archive.org/web/20171106160435/http://www.cnn.com/2008/LIVING/personal/04/04/facebook.love/index.html|url-status=live}}</ref>

Prior to social networking sites, technologies like [[short message service]] (SMS) and the telephone also had a significant impact on social interactions. In 2000, market research group [[Ipsos MORI]] reported that 81% of 15- to 24-year-old SMS users in the United Kingdom had used the service to coordinate social arrangements and 42% to flirt.<ref>[http://www.ipsos-mori.com/researchpublications/researcharchive/1575/I-Just-Text-To-Say-I-Love-You.aspx I Just Text To Say I Love You] {{Webarchive|url=https://web.archive.org/web/20161227091824/https://www.ipsos-mori.com/researchpublications/researcharchive/1575/I-Just-Text-To-Say-I-Love-You.aspx }}, Ipsos MORI, September 2005.</ref>

=== Entertainment, news, and advertising ===
{| class="wikitable" style="float:right; margin-left: 5px;"
|+News source preference of Americans in 2006.<ref>{{cite web|title=Online News: For many home broadband users, the internet is a primary news source|publisher=Pew Internet Project|url=http://www.ccgrouppr.com/PIP_News.and.Broadband.pdf|url-status=dead|archive-url=https://web.archive.org/web/20131021122359/http://www.ccgrouppr.com/PIP_News.and.Broadband.pdf|archive-date=21 October 2013}}</ref>
|-
| Local TV || 59%
|-
| National TV || 47%
|-
| Radio || 44%
|-
| Local paper || 38%
|-
| Internet || 23%
|-
| National paper || 12%
|-
| colspan = 2|<small>Survey permitted multiple answers</small>
|}
In cultural terms, telecommunication has increased the public's ability to access music and film. With television, people can watch films they have not seen before in their own home without having to travel to the video store or cinema. With radio and the Internet, people can listen to music they have not heard before without having to travel to the music store.

Telecommunication has also transformed the way people receive their news. A 2006 survey (right table) of slightly more than 3,000 Americans by the non-profit Pew Internet and American Life Project in the United States the majority specified television or radio over newspapers.

Telecommunication has had an equally significant impact on advertising. [[TNS Media Intelligence]] reported that in 2007, 58% of advertising expenditure in the United States was spent on media that depend upon telecommunication.<ref>{{cite magazine|title=100 Leading National Advertisers|magazine=Advertising Age|url=http://adage.com/images/random/datacenter/2008/spendtrends08.pdf|access-date=21 June 2009|archive-date=27 July 2011|archive-url=https://web.archive.org/web/20110727231038/http://adage.com/images/random/datacenter/2008/spendtrends08.pdf|url-status=live}}</ref>

{| class="wikitable"
|+Advertising expenditures in US in 2007
|-
!Medium || || Spending
|-
| Internet || 7.6% ||$11.31 billion
|-
| Radio || 7.2% ||$10.69 billion
|-
| Cable TV || 12.1% ||$18.02 billion
|-
| Syndicated TV || 2.8% ||$4.17 billion
|-
| Spot TV || 11.3% ||$16.82 billion
|-
| Network TV || 17.1% ||$25.42 billion
|-
| Newspaper || 18.9% ||$28.22 billion
|-
| Magazine || 20.4% ||$30.33 billion
|-
| Outdoor || 2.7% ||$4.02 billion
|-
| Total || 100% ||$149 billion
|-
|}

== Regulation ==
Many countries have enacted legislation which conforms to the International Telecommunication Regulations established by the International Telecommunication Union (ITU), which is the "leading UN agency for information and communication technology issues".<ref>[http://www.itu.int/net/about/index.aspx International Telecommunication Union : About ITU] {{Webarchive|url=https://web.archive.org/web/20090715225630/http://www.itu.int/net/about/index.aspx }}. ITU. Accessed 21 July 2009. ([https://www.itu.int/osg/csd/wtpf/wtpf2009/documents/ITU_ITRs_88.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20110607104643/https://www.itu.int/osg/csd/wtpf/wtpf2009/documents/ITU_ITRs_88.pdf }} of regulation)</ref> In 1947, at the Atlantic City Conference, the ITU decided to "afford international protection to all frequencies registered in a new international frequency list and used in conformity with the Radio Regulation". According to the ITU's ''Radio Regulations'' adopted in Atlantic City, all frequencies referenced in the ''International Frequency Registration Board'', examined by the board and registered on the ''International Frequency List'' "shall have the right to international protection from harmful interference".<ref>{{cite journal|doi=10.1017/S0002930000170046|jstor=2194872|title=Jamming and the Protection of Frequency Assignments|year=1955|last1=Codding|first1=George A.|journal=American Journal of International Law|volume=49|issue=3|pages=384–388}}.</ref>

From a global perspective, there have been political debates and legislation regarding the management of telecommunication and broadcasting. The [[history of broadcasting]] discusses some debates in relation to balancing conventional communication such as printing and telecommunication such as radio broadcasting.<ref name="Wood" /> The onset of [[World War II]] brought on the first explosion of international broadcasting propaganda.<ref name="Wood">{{cite book|last=Wood|first=James|title=History of international broadcasting|year=1992|page=2|isbn=9780863413025}}</ref> Countries, their governments, insurgents, terrorists, and militiamen have all used telecommunication and broadcasting techniques to promote propaganda.<ref name="Wood" /><ref name="Garfield">{{Cite journal |journal=Middle East Quarterly |last=Garfield |first=Andrew |title=The U.S. Counter-propaganda Failure in Iraq |volume=14 |number=4 |pages=23–32 |url=https://www.meforum.org/1753/the-us-counter-propaganda-failure-in-iraq |url-status=live |archive-url=https://web.archive.org/web/20090302021425/http://www.meforum.org/1753/the-us-counter-propaganda-failure-in-iraq |archive-date=2 March 2009 |via=Middle East Forum}}</ref> Patriotic propaganda for political movements and colonization started the mid-1930s. In 1936, the BBC broadcast propaganda to the Arab World to partly counter similar broadcasts from Italy, which also had colonial interests in North Africa.<ref name="Wood" /> Modern political debates in telecommunication include the reclassification of [[Internet access|broadband Internet service]] as a telecommunications service (also called [[net neutrality]]),<ref name="NYT-20141110-EW">{{cite news |last=Wyatt |first=Edward |title=Obama Asks F.C.C. to Adopt Tough Net Neutrality Rules |url=https://www.nytimes.com/2014/11/11/technology/obama-net-neutrality-fcc.html |work=[[New York Times]] |access-date=15 November 2014 |archive-date=27 April 2019 |archive-url=https://web.archive.org/web/20190427132858/https://www.nytimes.com/2014/11/11/technology/obama-net-neutrality-fcc.html |url-status=live }}</ref><ref name="NYT-20141114">{{cite news |title=Why the F.C.C. Should Heed President Obama on Internet Regulation |url=https://www.nytimes.com/2014/11/15/opinion/why-the-fcc-should-heed-president-obama-on-internet-regulations.html |work=[[New York Times]] |access-date=15 November 2014 |archive-date=9 July 2018 |archive-url=https://web.archive.org/web/20180709134910/https://www.nytimes.com/2014/11/15/opinion/why-the-fcc-should-heed-president-obama-on-internet-regulations.html |url-status=live }}</ref> regulation of [[Mobile phone spam|phone spam]],<ref>{{cite web |last1=McGill |first1=Margaret Harding |title=FCC takes long-delayed step against spam text surge |url=https://www.axios.com/2022/09/26/fcc-spam-texts-proposal-approved |website=Axios |access-date=8 February 2023 |language=en |archive-date=8 February 2023 |archive-url=https://web.archive.org/web/20230208150751/https://www.axios.com/2022/09/26/fcc-spam-texts-proposal-approved |url-status=live }}</ref><ref>{{cite web |last1=Hall |first1=Madison |title=Robocallers are preying on the elderly with fake Medicare calls. It's a no-brainer to stop it, but nobody has. |url=https://www.businessinsider.com/robocalls-medicare-fraud-how-to-stop-2023-2 |website=Business Insider |access-date=8 February 2023 |archive-date=7 February 2023 |archive-url=https://web.archive.org/web/20230207232314/https://www.businessinsider.com/robocalls-medicare-fraud-how-to-stop-2023-2 |url-status=live }}</ref> and expanding affordable broadband access.<ref>{{cite web |title=Affordable Broadband: FCC Could Improve Performance Goals and Measures, Consumer Outreach, and Fraud Risk Management |url=https://www.gao.gov/products/gao-23-105399 |website=www.gao.gov |access-date=8 February 2023 |language=en |archive-date=8 February 2023 |archive-url=https://web.archive.org/web/20230208150801/https://www.gao.gov/products/gao-23-105399 |url-status=live }}</ref>

==Modern media==
=== Worldwide equipment sales ===
According to data collected by Gartner<ref>{{Cite news|last=Arthur|first=Charles|title=Why falling PC sales means Windows 7 is on the way|work=The Guardian|url=https://www.theguardian.com/technology/blog/2009/mar/04/computing-windows-sales|access-date=6 June 2023|issn=0261-3077|url-status=live|archive-url=https://web.archive.org/web/20170519070556/https://www.theguardian.com/technology/blog/2009/mar/04/computing-windows-sales |archive-date=19 May 2017}}</ref><ref>{{Cite web|title=Mobile Phone Sales To Exceed One Billion in 2009|url=http://www.palminfocenter.com/view_story.asp?ID=7978|access-date=6 June 2023|website=Palm Infocenter|url-status=live|archive-url=https://web.archive.org/web/20180308042243/http://www.palminfocenter.com/view_story.asp?ID=7978 |archive-date=8 March 2018}}</ref> and Ars Technica<ref>{{Cite web|last=Reimer|first=Jeremy|title=Total share: 30 years of personal computer market share figures|url=https://arstechnica.com/features/2005/12/total-share/|access-date=6 June 2023|website=Ars Technica|url-status=live|archive-url=https://web.archive.org/web/20150512015006/http://www.360doc.com/content/12/0124/10/28217_181627497.shtml |archive-date=12 May 2015}}</ref> sales of main consumer's telecommunication equipment worldwide in millions of units was:
{| class="wikitable"
|-
! Equipment / year !! 1975 !! 1980 !! 1985 !! 1990 !! 1994 !! 1996 !! 1998 !! 2000 !! 2002 !! 2004 !! 2006 !! 2008
|-
| Computers || 0 || 1 || 8 || 20 || 40 || 75 || 100 || 135 || 130 || 175 || 230 || 280
|-
| Cell phones || N/A || N/A || N/A || N/A || N/A || N/A || 180 || 400 || 420 || 660 || 830 || 1000
|}

=== Telephone ===
[[File:Fibreoptic.jpg|thumb|upright|[[Optical fiber]] provides cheaper bandwidth for long-distance communication.]]

In a telephone network, the caller is connected to the person to whom they wish to talk by switches at various [[telephone exchanges]]. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller [[pulse dialing|dials]] the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small [[microphone]] in the caller's [[handset]]. This electrical signal is then sent through the network to the user at the other end where it is transformed back into sound by a small [[loudspeaker|speaker]] in that person's handset.

{{As of|2015}}, the landline telephones in most residential homes are analog—that is, the speaker's voice directly determines the signal's voltage.<ref>{{cite book|isbn=978-1305855779|page=433|title=Engineering and Technology|last1=Hacker|first1=Michael|last2=Burghardt|first2=David|last3=Fletcher|first3=Linnea|last4=Gordon|first4=Anthony|last5=Peruzzi|first5=William}}</ref> Although short-distance calls may be handled from end-to-end as analog signals, increasingly telephone service providers are transparently converting the signals to digital signals for transmission. The advantage of this is that digitized voice data can travel side by side with data from the Internet and can be perfectly reproduced in long-distance communication (as opposed to analog signals that are inevitably impacted by noise).

Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m).<ref>{{Cite press release |url=http://www.gartner.com/press_releases/asset_145891_11.html |title=Gartner Says Top Six Vendors Drive Worldwide Mobile Phone Sales to 21% Growth in 2005 |publisher=Gartner |archive-url=https://web.archive.org/web/20120510220444/http://www.gartner.com/press_releases/asset_145891_11.html |archive-date=10 May 2012}}</ref> In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth.<ref>{{cite journal|doi=10.1109/MSPEC.2006.1628825|title=Africa calling [African wireless connection]|year=2006|last1=Mbarika|first1=V.W.A.|last2=Mbarika|first2=I.|journal=IEEE Spectrum|volume=43|issue=5|pages=56–60|s2cid=30385268}}</ref> Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as [[GSM]] or [[W-CDMA]] with many markets choosing to deprecate analog systems such as [[Advanced Mobile Phone System|AMPS]].<ref>[http://www.amta.org.au/default.asp?Page=142 Ten Years of GSM in Australia] {{webarchive|url=https://web.archive.org/web/20080720110058/http://www.amta.org.au/default.asp?Page=142 }}, Australia Telecommunications Association, 2003.</ref>

There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of [[TAT-8]] in 1988, the 1990s saw the widespread adoption of systems based on optical fibers. The benefit of communicating with optical fibers is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optical fibre cables are able to carry 25 times as many telephone calls as TAT-8.<ref>[http://www.att.com/history/milestones.html Milestones in AT&T History] {{Webarchive|url=https://web.archive.org/web/20080906003711/http://www.att.com/history/milestones.html }}, AT&T Knowledge Ventures, 2006.</ref> This increase in data capacity is due to several factors: First, optical fibres are physically much smaller than competing technologies. Second, they do not suffer from [[crosstalk (electronics)|crosstalk]] which means several hundred of them can be easily bundled together in a single cable.<ref>[http://www.cs.ucl.ac.uk/staff/S.Bhatti/D51-notes/node21.html Optical fibre waveguide] {{Webarchive|url=https://web.archive.org/web/20060524033058/http://www.cs.ucl.ac.uk/staff/S.Bhatti/D51-notes/node21.html }}, Saleem Bhatti, 1995.</ref> Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.<ref>[http://www.cisco.com/univercd/cc/td/doc/product/mels/cm1500/dwdm/dwdm_ovr.pdf Fundamentals of DWDM Technology] {{Webarchive|url=https://web.archive.org/web/20120809084728/http://www.cisco.com/univercd/cc/td/doc/product/mels/cm1500/dwdm/dwdm_ovr.pdf }}, CISCO Systems, 2006.</ref><ref>{{Cite web |url=http://www.lightreading.com/document.asp?doc_id=31358 |title=Report: DWDM No Match for Sonet |first=Mary |last=Jander |website=Light Reading |archive-url=https://web.archive.org/web/20120724081909/http://www.lightreading.com/document.asp?doc_id=31358 |archive-date=24 July 2012}}</ref>

Assisting communication across many modern optical fibre networks is a protocol known as [[Asynchronous Transfer Mode]] (ATM). The ATM protocol allows for the side-by-side [[data transmission]] mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a [[traffic contract]] with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut off completely.<ref>{{cite book | last = Stallings | first = William | edition= 7th intl | title = Data and Computer Communications | url = https://archive.org/details/datacomputercomm00stal_1 | url-access = registration | publisher = Pearson Prentice Hall | year = 2004 | pages = [https://archive.org/details/datacomputercomm00stal_1/page/337 337–66] | isbn = 978-0-13-183311-1 }}</ref> There are competitors to ATM, such as [[Multiprotocol Label Switching]] (MPLS), that perform a similar task and are expected to supplant ATM in the future.<ref>[http://www.networkworld.com/columnists/2002/0812edit.html MPLS is the future, but ATM hangs on] {{Webarchive|url=https://web.archive.org/web/20070706034545/http://www.networkworld.com/columnists/2002/0812edit.html }}, John Dix, Network World, 2002</ref><ref>{{cite news|last=Lazar|first=Irwin|title=The WAN Road Ahead: Ethernet or Bust?|url=http://www.telarus.com/industry/the-wan-road-ahead:-ethernet-or-bust.html|access-date=22 February 2011|newspaper=Telecom Industry Updates|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402021712/http://www.telarus.com/industry/the-wan-road-ahead:-ethernet-or-bust.html|url-status=dead}}</ref>

=== Radio and television ===
{{Main|Radio|Television|Broadcasting}}
[[File:Digital broadcast standards.svg|thumb|upright=1.35|[[Digital television]] standards and their adoption worldwide]]

In a broadcast system, the central high-powered [[radio masts and towers|broadcast tower]] transmits a high-frequency [[electromagnetic wave]] to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The receiver is then [[antenna tuner|tuned]] so as to pick up the high-frequency wave and a [[demodulator]] is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analog (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).<ref name="stallings-intro" /><ref>{{Cite web|title=How Radio Works|url=https://electronics.howstuffworks.com/radio.htm|access-date=2023-02-12|website=HowStuffWorks|language=en-us|archive-date=2 January 2016|archive-url=https://web.archive.org/web/20160102215734/http://www.howstuffworks.com/radio.htm|url-status=live}}</ref>

The [[broadcast media industry]] is at a critical turning point in its development, with many countries moving from analog to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable [[integrated circuit]]s. The chief advantage of digital broadcasts is that they prevent a number of complaints common to traditional analog broadcasts. For television, this includes the elimination of problems such as [[noise (video)|snowy pictures]], [[television interference (ghosting)|ghosting]] and other distortion. These occur because of the nature of analog transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011— a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using [[forward error correction]] a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.<ref>{{Cite web|title=Digital Television in Australia|url=https://www.digitaltv.com.au/|access-date=6 June 2023|website=Digital Television News Australia|url-status=live|archive-url=https://web.archive.org/web/20180312123813/https://digitaltv.com.au/|archive-date=12 March 2018}}</ref><ref>{{cite book | last = Stallings | first = William | edition= 7th intl | title = Data and Computer Communications | url = https://archive.org/details/datacomputercomm00stal_1 | url-access = registration | publisher = Pearson Prentice Hall | year = 2004 | isbn = 978-0-13-183311-1 }}</ref>

In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the [[ATSC Standards|ATSC]], [[Digital Video Broadcasting|DVB]] and [[ISDB]] standards; the adoption of these standards thus far is presented in the captioned map. All three standards use [[MPEG-2]] for video compression. ATSC uses [[Dolby Digital]] AC-3 for audio compression, ISDB uses [[Advanced Audio Coding]] (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses [[MPEG-1]] Part 3 Layer 2.<ref>[http://www.dynamix.ca/doc/HDVhandbook1.pdf HDV Technology Handbook] {{Webarchive|url=https://web.archive.org/web/20060623142640/http://www.dynamix.ca/doc/HDVhandbook1.pdf }}, [[Sony]], 2004.</ref><ref>[http://www.dvb.org/technology/standards_specifications/audio/index.xml Audio] {{Webarchive|url=https://web.archive.org/web/20060927002250/http://www.dvb.org/technology/standards_specifications/audio/index.xml }}, Digital Video Broadcasting Project, 2003, archived from [http://www.dvb.org/technology/standards_specifications/audio/ the original] 27 September 2006.</ref> The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the [[Digital Audio Broadcasting]] standard (also known as the [[Eureka 147]] standard). The exception is the United States which has chosen to adopt [[HD Radio]]. HD Radio, unlike Eureka 147, is based upon a transmission method known as [[in-band on-channel]] transmission that allows digital information to "piggyback" on normal AM or FM analog transmissions.<ref>[http://www.worlddab.org/cstatus.aspx Status of DAB (US)] {{Webarchive|url=https://web.archive.org/web/20060721060832/http://www.worlddab.org/cstatus.aspx }}, World DAB Forum, March 2005.</ref>  

However, despite the pending switch to digital, analog television remains being transmitted in most countries. An exception is the United States that ended analog television transmission (by all but the very low-power TV stations) on 12 June 2009<ref>{{cite news | author=Brian Stelter | title=Changeover to Digital TV Off to a Smooth Start | url=https://www.nytimes.com/2009/06/14/business/media/14digital.html?_r=2&hp | work=New York Times | date=13 June 2009 | access-date=25 February 2017 | archive-date=14 December 2017 | archive-url=https://web.archive.org/web/20171214130110/http://www.nytimes.com/2009/06/14/business/media/14digital.html?_r=2&hp | url-status=live }}</ref> after twice delaying the switchover deadline. Kenya also ended analog television transmission in December 2014 after multiple delays. For analog television, there were three standards in use for broadcasting color TV (see a map on adoption [[:File:NTSC-PAL-SECAM.png|here]]). These are known as [[PAL]] (German designed), [[NTSC]] (American designed), and [[SECAM]] (French-designed). For analog radio, the switch to digital radio is made more difficult by the higher cost of digital receivers.<ref>[http://www.worlddab.org/dabprod.aspx DAB Products] {{Webarchive|url=https://web.archive.org/web/20060621082027/http://www.worlddab.org/dabprod.aspx }}, World DAB Forum, 2006.</ref> The choice of modulation for analog radio is typically between amplitude ('''AM''') or frequency modulation ('''FM'''). To achieve [[stereophonic sound|stereo playback]], an amplitude modulated subcarrier is used for [[stereo FM]], and quadrature amplitude modulation is used for stereo AM or [[C-QUAM]].

=== Internet ===
[[File:OSI Model v1.svg|upright=1.2|thumb|The [[OSI reference model]]]]

The Internet is a worldwide network of computers and computer networks that communicate with each other using the [[Internet Protocol]] (IP).<ref>{{Cite web |url=http://www.cnri.reston.va.us/what_is_internet.html |title=What Is The Internet (And What Makes It Work) |first1=Robert |last1=Kahn |first2=Vinton G. |last2=Cerf |website=Corporation for National Research Initiatives (CNRI) |url-status=live |access-date=6 June 2023 |archive-url=https://web.archive.org/web/20170715105113/http://www.cnri.reston.va.us/what_is_internet.html |archive-date=15 July 2017}} Specifically see footnote xv.</ref> Any computer on the Internet has a unique [[IP address]] that can be used by other computers to route information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. The Internet is thus an exchange of messages between computers.<ref>{{cite web |url=http://computer.howstuffworks.com/internet-infrastructure.htm |title=How Internet Infrastructure Works |website=Computer.HowStuffWorks.com |year=2007 |author=Jeff Tyson |access-date=22 May 2007 |archive-date=10 April 2010 |archive-url=https://web.archive.org/web/20100410162047/http://computer.howstuffworks.com/internet-infrastructure.htm |url-status=live }}</ref>

It is estimated that 51% of the information flowing through two-way telecommunications networks in the year 2000 were flowing through the Internet (most of the rest (42%) through the [[landline telephone]]). By 2007 the Internet clearly dominated and captured 97% of all the information in telecommunication networks (most of the rest (2%) through [[mobile phones]]).<ref name="HilbertLopez2011"/> {{As of|2008}}, an estimated 21.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (73.6%), Oceania/Australia (59.5%) and Europe (48.1%).<ref>{{Cite web|title=World Internet Users and Population Stats|url=https://www.internetworldstats.com/stats.htm|website=Internet World Stats|archive-url=https://web.archive.org/web/20090202142301/http://internetworldstats.com/stats.htm |archive-date=2 February 2009}}</ref> In terms of [[Broadband Internet access|broadband access]], Iceland (26.7%), South Korea (25.4%) and the Netherlands (25.3%) led the world.<ref>{{Cite web |title=OECD Broadband Statistics, December 2005 |url=http://www.oecd.org/document/39/0,2340,en_2649_34225_36459431_1_1_1_1,00.html |website=OECD |archive-url=https://web.archive.org/web/20090106012350/http://www.oecd.org/document/39/0,2340,en_2649_34225_36459431_1_1_1_1,00.html |archive-date=6 January 2009}}</ref>

The Internet works in part because of [[communications protocol|protocols]] that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an [[Internet browser]] to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or [[Wi-Fi]] connection. Protocols are often talked about in terms of their place in the OSI reference model (pictured on the right), which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.<ref>{{Cite web|title=The TCP/IP Guide - History of the OSI Reference Model|url=http://www.tcpipguide.com/free/t_HistoryoftheOSIReferenceModel.htm|first=Charles M.|last=Kozierok|access-date=6 June 2023|website=The TCP/IP Guide|url-status=live|archive-url=https://web.archive.org/web/20170904204159/http://www.tcpipguide.com/free/t_HistoryoftheOSIReferenceModel.htm |archive-date=4 September 2017 }}</ref>

For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fiber. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.

At the network layer, things become standardized with the Internet Protocol (IP) being adopted for [[logical address]]ing. For the World Wide Web, these "IP addresses" are derived from the human-readable form using the [[Domain Name System]] (e.g. 72.14.207.99 is derived from www.google.com). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.<ref>[https://www.microsoft.com/technet/itsolutions/network/ipv6/introipv6.mspx Introduction to IPv6] {{Webarchive|url=https://web.archive.org/web/20081013065951/http://www.microsoft.com/technet/itsolutions/network/ipv6/introipv6.mspx }}, Microsoft Corporation, February 2006.</ref> 

At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the [[User Datagram Protocol]] (UDP). TCP is used when it is essential every message sent is received by the other computer whereas UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered nor retransmitted if lost. Both TCP and UDP packets carry [[TCP and UDP port|port numbers]] with them to specify what application or [[process (computing)|process]] the packet should be handled by.<ref>Stallings, pp. 683–702.</ref> Because certain application-level protocols use [[List of TCP and UDP port numbers|certain ports]], network administrators can manipulate traffic to suit particular requirements. Examples are to restrict Internet access by blocking the traffic destined for a particular port or to affect the performance of certain applications by assigning [[WAN optimization|priority]].

Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the [[Secure Sockets Layer]] (SSL) and [[Transport Layer Security]] (TLS) protocols. These protocols ensure that data transferred between two parties remains completely confidential.<ref>T. Dierks and C. Allen, The TLS Protocol Version 1.0, RFC 2246, 1999.</ref> Finally, at the application layer, are many of the protocols Internet users would be familiar with such as [[HTTP]] (web browsing), [[POP3]] (e-mail), [[File Transfer Protocol|FTP]] (file transfer), [[IRC]] (Internet chat), [[BitTorrent (protocol)|BitTorrent]] (file sharing) and [[XMPP]] (instant messaging).

[[VoIP|Voice over Internet Protocol]] (VoIP) allows data packets to be used for [[synchronous]] voice communications. The data packets are marked as voice type packets and can be prioritized by the network administrators so that the real-time, synchronous conversation is less subject to contention with other types of data traffic which can be delayed (i.e. file transfer or email) or buffered in advance (i.e. audio and video) without detriment. That prioritization is fine when the network has sufficient capacity for all the VoIP calls taking place at the same time and the network is enabled for prioritization i.e. a private corporate-style network, but the Internet is not generally managed in this way and so there can be a big difference in the quality of VoIP calls over a private network and over the public Internet.<ref>{{cite web|url= http://www.telecomsadvice.org.uk/infosheets/voip_voice_over_internet_protocol_and_internet_telephony.htm|title= VoIP, Voice over Internet Protocol and Internet telephone calls|last= Multimedia|first= Crucible|access-date= 30 June 2011|archive-date= 24 January 2018|archive-url= https://web.archive.org/web/20180124045522/http://www.telecomsadvice.org.uk/infosheets/voip_voice_over_internet_protocol_and_internet_telephony.htm|url-status= live}}</ref>

=== Local area networks and wide area networks ===
Despite the growth of the Internet, the characteristics of [[local area network]]s (LANs)—computer networks that do not extend beyond a few kilometres—remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them. When they are not connected with the Internet, they also have the advantages of privacy and security. However, purposefully lacking a direct connection to the Internet does not provide assured protection from hackers, military forces, or economic powers. These threats exist if there are any methods for connecting remotely to the LAN.

[[Wide area network]]s (WANs) are private computer networks that may extend for thousands of kilometres. Once again, some of their advantages include privacy and security. Prime users of private LANs and WANs include armed forces and intelligence agencies that must keep their information secure and secret.

In the mid-1980s, several sets of communication protocols emerged to fill the gaps between the data-link layer and the application layer of the [[OSI reference model]]. These included [[AppleTalk]], [[IPX]], and [[NetBIOS]] with the dominant protocol set during the early 1990s being IPX due to its popularity with [[MS-DOS]] users. [[TCP/IP]] existed at this point, but it was typically only used by large government and research facilities.<ref>Martin, Michael (2000). ''Understanding the Network'' ([http://www.informit.com/content/images/0735709777/samplechapter/0735709777.pdf The Networker's Guide to AppleTalk, IPX, and NetBIOS] {{Webarchive|url=https://web.archive.org/web/20090329054333/http://www.informit.com/content/images/0735709777/samplechapter/0735709777.pdf }}), SAMS Publishing, {{ISBN|0-7357-0977-7}}.</ref>

As the Internet grew in popularity and its traffic was required to be routed into private networks, the TCP/IP protocols replaced existing local area network technologies. Additional technologies, such as [[DHCP]], allowed TCP/IP-based computers to self-configure in the network. Such functions also existed in the AppleTalk/ IPX/ NetBIOS protocol sets.<ref>Ralph Droms, [http://www.dhcp.org/ Resources for DHCP] {{Webarchive|url=https://web.archive.org/web/20070704061131/http://www.dhcp.org/ }}, November 2003.</ref>

Whereas Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) are typical data-link protocols for larger networks such as WANs; Ethernet and Token Ring are typical data-link protocols for LANs. These protocols differ from the former protocols in that they are simpler, e.g., they omit features such as [[quality of service]] guarantees, and offer [[medium access control]]. Both of these differences allow for more economical systems.<ref>Stallings, pp. 500–26.</ref>

Despite the modest popularity of Token Ring in the 1980s and 1990s, virtually all LANs now use either wired or wireless Ethernet facilities. At the physical layer, most wired Ethernet implementations use [[twisted pair|copper twisted-pair cables]] (including the common [[10BASE-T]] networks). However, some early implementations used heavier coaxial cables and some recent implementations (especially high-speed ones) use optical fibers.<ref>Stallings, pp. 514–16.</ref> When optic fibers are used, the distinction must be made between multimode fibers and single-mode fibers. [[Multi-mode optical fiber|Multimode fibers]] can be thought of as thicker optical fibers that are cheaper to manufacture devices for, but that suffer from less usable bandwidth and worse attenuation—implying poorer long-distance performance.<ref>{{Cite web|title=Fiber Optic Cable single-mode multi-mode Tutorial|url=https://arcelect.com/fibercable.htm|access-date=6 June 2023 |website=ARC Electronics |url-status=live |archive-url=https://web.archive.org/web/20181023040952/https://arcelect.com/fibercable.htm |archive-date=23 October 2018}}</ref>

== See also ==
{{Portal|Telecommunications}}
{{columns-list|colwidth=30em|
* [[Underwater acoustic communication]]
* [[Active networking]]
* [[Digital Revolution]]
* [[Information Age]]
* [[International Teletraffic Congress]]
* [[List of telecommunications encryption terms]]
* [[Nanonetwork]]
* [[New media]]
* [[Outline of telecommunication]]
* [[Telecommunications Industry Association]]
* [[Telecoms resilience]]
* [[Telemetry]]
* [[Wavelength-division multiplexing]]
* [[Wired communication]]
}}

== References ==

=== Citations ===
{{Reflist}}

=== Bibliography ===
* [[Gerard Goggin|Goggin, Gerard]], ''Global Mobile Media'' (New York: Routledge, 2011), p. 176. {{ISBN|978-0-415-46918-0}}.
* [[Organisation for Economic Co-operation and Development|OECD]], [https://books.google.com/books?id=WpmzcqmgMbAC&q=universal+service+and+rate+restructuring+in+telecommunications ''Universal Service and Rate Restructuring in Telecommunications''], Organisation for Economic Co-operation and Development (OECD) Publishing, 1991. {{ISBN|92-64-13497-2}}.
* Wheen, Andrew. ''Dot-Dash to Dot.Com: How Modern Telecommunications Evolved from the Telegraph to the Internet'' (Springer, 2011).

== External links ==
* [http://itc-conference.org/ International Teletraffic Congress]
* [http://www.itu.int International Telecommunication Union (ITU)]
* [https://web.archive.org/web/20080302071329/http://www.atis.org/tg2k/ ATIS Telecom Glossary]
* [http://www.fcc.gov/ Federal Communications Commission]
* [http://www.comsoc.org/ IEEE Communications Society]
* [http://www.itu.int/home/ International Telecommunication Union]
* {{webarchive |url=https://web.archive.org/web/20040413074912/http://www.ericsson.com/support/telecom/index.shtml |title=Ericsson's Understanding Telecommunications }} (Ericsson removed the book from their site in September 2005)

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