Internet

== Infrastructure ==
{{See also|List of countries by number of Internet users|List of countries by Internet connection speeds}}
[[File:World map of submarine cables.png|thumb|2007 map showing submarine fiberoptic telecommunication cables around the world]]
The communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. As with any computer network, the Internet physically consists of [[router (computing)|router]]s, media (such as cabling and radio links), repeaters, modems etc. However, as an example of [[internetworking]], many of the network nodes are not necessarily Internet equipment per se, the internet packets are carried by other full-fledged networking protocols with the Internet acting as a homogeneous networking standard, running across [[heterogeneous]] hardware, with the packets guided to their destinations by IP routers.

=== Service tiers ===
[[File:Internet Connectivity Distribution & Core.svg|thumb|Packet routing across the Internet involves several tiers of Internet service providers.]]

[[Internet service provider]]s (ISPs) establish the worldwide connectivity between individual networks at various levels of scope. End-users who only access the Internet when needed to perform a function or obtain information, represent the bottom of the routing hierarchy. At the top of the routing hierarchy are the [[tier 1 network]]s, large telecommunication companies that exchange traffic directly with each other via very high speed [[fiber-optic cable]]s and governed by [[peering]] agreements. [[Tier 2 network|Tier 2]] and lower-level networks buy [[Internet transit]] from other providers to reach at least some parties on the global Internet, though they may also engage in peering. An ISP may use a single upstream provider for connectivity, or implement [[multihoming]] to achieve redundancy and load balancing. [[Internet exchange point]]s are major traffic exchanges with physical connections to multiple ISPs. Large organizations, such as academic institutions, large enterprises, and governments, may perform the same function as ISPs, engaging in peering and purchasing transit on behalf of their internal networks. Research networks tend to interconnect with large subnetworks such as [[GEANT]], [[GLORIAD]], [[Internet2]], and the UK's [[national research and education network]], [[JANET]].

=== Access ===
Common methods of [[Internet access]] by users include dial-up with a computer [[modem]] via telephone circuits, [[broadband]] over [[coaxial cable]], [[Optical fiber|fiber optics]] or copper wires, [[Wi-Fi]], [[Satellite Internet|satellite]], and [[mobile telephony|cellular telephone]] technology (e.g. [[3G]], [[4G]]). The Internet may often be accessed from computers in libraries and [[Internet café]]s. [[Internet kiosk|Internet access points]] exist in many public places such as airport halls and coffee shops. Various terms are used, such as ''public Internet kiosk'', ''public access terminal'', and ''Web [[payphone]]''. Many hotels also have public terminals that are usually fee-based. These terminals are widely accessed for various usages, such as ticket booking, bank deposit, or [[online payment]]. Wi-Fi provides wireless access to the Internet via local computer networks. [[Hotspot (Wi-Fi)|Hotspots]] providing such access include Wi-Fi cafés, where users need to bring their own wireless devices, such as a laptop or [[Personal Digital Assistant|PDA]]. These services may be free to all, free to customers only, or fee-based.

[[Grassroots]] efforts have led to [[wireless community network]]s. Commercial Wi-Fi services that cover large areas are available in many cities, such as [[New York City|New York]], [[London]], [[Vienna]], [[Toronto]], [[San Francisco]], [[Philadelphia]], [[Chicago]] and [[Pittsburgh]], where the Internet can then be accessed from places such as a park bench.<ref>{{cite web|last=Pasternak |first=Sean B. |url=https://www.bloomberg.com/apps/news?pid=10000082&sid=aQ0ZfhMa4XGQ |title=Toronto Hydro to Install Wireless Network in Downtown Toronto |publisher=Bloomberg |date=7 March 2006 |access-date=8 August 2011 |url-status=live |archive-url=https://web.archive.org/web/20060410104717/http://www.bloomberg.com/apps/news?pid=10000082&sid=aQ0ZfhMa4XGQ |archive-date=10 April 2006 }}</ref> Experiments have also been conducted with proprietary mobile wireless networks like [[Ricochet (Internet service)|Ricochet]], various high-speed data services over cellular networks, and fixed wireless services. Modern [[smartphone]]s can also access the Internet through the cellular carrier network. For Web browsing, these devices provide applications such as [[Google Chrome]], [[Safari (web browser)|Safari]], and [[Firefox]] and a wide variety of other Internet software may be installed from [[app store]]s. Internet usage by mobile and tablet devices exceeded desktop worldwide for the first time in October 2016.<ref>{{cite web|quote=StatCounter Global Stats finds that mobile and tablet devices accounted for 51.3% of Internet usage worldwide in October compared to 48.7% by desktop.|url=http://gs.statcounter.com/press/mobile-and-tablet-internet-usage-exceeds-desktop-for-first-time-worldwide|title=Mobile and Tablet Internet Usage Exceeds Desktop for First Time Worldwide|archive-url=https://web.archive.org/web/20161101170640/http://gs.statcounter.com/press/mobile-and-tablet-internet-usage-exceeds-desktop-for-first-time-worldwide|archive-date=1 November 2016|website=StatCounter: Global Stats, Press Release|date=1 November 2016}}</ref>

====Mobile communication====
[[File:Number of mobile cellular subscriptions 2012-2016.svg|thumb|Number of mobile cellular subscriptions 2012–2016]] The [[International Telecommunication Union]] (ITU) estimated that, by the end of 2017, 48% of individual users regularly connect to the Internet, up from 34% in 2012.<ref>{{cite web|url=https://www.itu.int/en/ITU-D/Statistics/Pages/publications/wtid.aspx|title=World Telecommunication/ICT Indicators Database 2020 (24th Edition/July 2020)|archive-url=https://web.archive.org/web/20190421072228/https://www.itu.int/en/ITU-D/Statistics/Pages/publications/wtid.aspx|archive-date=21 April 2019|website=International Telecommunication Union (ITU)|date=2017a|quote=Key ICT indicators for developed and developing countries and the world (totals and penetration rates). World Telecommunication/ICT Indicators database}}</ref> [[Mobile Web|Mobile Internet]] connectivity has played an important role in expanding access in recent years, especially in [[Asia-Pacific|Asia and the Pacific]] and in Africa.<ref name="UNESCO">{{Cite book|url=http://unesdoc.unesco.org/images/0026/002610/261065e.pdf|title=World Trends in Freedom of Expression and Media Development Global Report 2017/2018|publisher=UNESCO|year=2018|access-date=29 May 2018|archive-date=20 September 2018|archive-url=https://web.archive.org/web/20180920181419/http://unesdoc.unesco.org/images/0026/002610/261065e.pdf|url-status=live}}</ref> The number of unique mobile cellular subscriptions increased from 3.9&nbsp;billion in 2012 to 4.8&nbsp;billion in 2016, two-thirds of the world's population, with more than half of subscriptions located in Asia and the Pacific. The number of subscriptions was predicted to rise to 5.7&nbsp;billion users in 2020.<ref name="GSMA The Mobile Economy 2019">{{Cite web|date=11 March 2019|title=GSMA The Mobile Economy 2019 |url=https://www.gsma.com/r/mobileeconomy/|access-date=28 November 2020|archive-url=https://web.archive.org/web/20190311062226/https://www.gsma.com/r/mobileeconomy/|archive-date=11 March 2019}}</ref> {{as of|2018}}, 80% of the world's population were covered by a [[4G]] network.<ref name="GSMA The Mobile Economy 2019" /> The limits that users face on accessing information via mobile applications coincide with a broader process of [[Fragmentation (computing)|fragmentation of the Internet]]. Fragmentation restricts access to media content and tends to affect the poorest users the most.<ref name="UNESCO" />

[[Zero-rating]], the practice of Internet service providers allowing users free connectivity to access specific content or applications without cost, has offered opportunities to surmount economic hurdles but has also been accused by its critics as creating a two-tiered Internet. To address the issues with zero-rating, an alternative model has emerged in the concept of 'equal rating' and is being tested in experiments by [[Mozilla]] and [[Orange S.A.|Orange]] in Africa. Equal rating prevents prioritization of one type of content and zero-rates all content up to a specified data cap. In a study published by [[Chatham House]], 15 out of 19 countries researched in Latin America had some kind of hybrid or zero-rated product offered. Some countries in the region had a handful of plans to choose from (across all mobile network operators) while others, such as [[Colombia]], offered as many as 30 pre-paid and 34 post-paid plans.<ref>{{Cite web|last=Galpaya|first=Helani|date=12 April 2019|title=Zero-rating in Emerging Economies|url=https://www.cigionline.org/sites/default/files/documents/GCIG%20no.47_1.pdf|url-status=live|archive-url=https://web.archive.org/web/20190412062932/https://www.cigionline.org/sites/default/files/documents/GCIG%20no.47_1.pdf|archive-date=12 April 2019|access-date=28 November 2020|website=Global Commission on Internet Governance}}</ref>

A study of eight countries in the [[Global South]] found that zero-rated data plans exist in every country, although there is a great range in the frequency with which they are offered and actually used in each.<ref>{{Cite web|url=http://a4ai.org/the-impacts-of-emerging-mobiledata-services-in-developing-countries/|title=Alliance for Affordable Internet (A4AI). 2015. Models of Mobile Data Services in Developing Countries. Research brief. The Impacts of Emerging Mobile Data Services in Developing Countries.}}</ref> The study looked at the top three to five carriers by market share in Bangladesh, Colombia, Ghana, India, Kenya, Nigeria, Peru and Philippines. Across the 181 plans examined, 13 percent were offering zero-rated services. Another study, covering [[Ghana]], [[Kenya]], [[Nigeria]] and [[South Africa]], found [[Facebook]]'s Free Basics and [[Wikipedia Zero]] to be the most commonly zero-rated content.<ref>{{Cite web|last1= Gillwald|first1= Alison|first2=Chenai|last2=Chair|first3=Ariel |last3=Futter |first4=Kweku|last4=  Koranteng |first5=Fola |last5= Odufuwa|first6= John|last6= Walubengo|date=12 September 2016|title=Much Ado About Nothing? Zero Rating in the African Context|url=https://researchictafrica.net/publications/Other_publications/2016_RIA_Zero-Rating_Policy_Paper_-_Much_ado_about_nothing.pdf|access-date=28 November 2020|website=Researchictafrica|archive-date=16 December 2020|archive-url=https://web.archive.org/web/20201216150858/https://researchictafrica.net/publications/Other_publications/2016_RIA_Zero-Rating_Policy_Paper_-_Much_ado_about_nothing.pdf|url-status=live}}</ref>