Internet

People online

About 6 billion, roughly three quarters of the world's population (ITU estimate)^[1]

People offline

About 2.2 billion, 96% of them in low- and middle-income countries^[1]

First network link

ARPANET, UCLA to SRI, fall 1969^[2]

Switch to TCP/IP

Jan 1, 1983, on ARPANET^[2]

Traffic over IPv6

50.1% of Google's traffic on one day, March 28, 2026; other measures are lower^[8]

Government shutdowns counted

At least 313 in 52 countries in 2025 (Access Now)^[10]

Origins

The Internet's central idea, breaking data into small packets that travel independently, took shape in the 1960s in separate lines of work. Leonard Kleinrock published on the theory in 1961, Paul Baran at RAND studied packet networks for secure military voice, and Donald Davies's group at the National Physical Laboratory in the United Kingdom supplied the word "packet." In 1962 J.C.R. Licklider wrote of a "Galactic Network" linking computers across the globe.^[2]

2:22 What packet switching means DW Shift explains how a message is broken into packets that travel separately and are reassembled.

ARPANET, funded by the defense research agency of the United States, put those ideas to use. The first packet switch was installed at UCLA in September 1969, the first host-to-host message went to the Stanford Research Institute (SRI) the next month, and four sites were connected by year's end. Ray Tomlinson wrote basic email software for it in 1972, and email quickly became a main use of the network.^[2]

3:22 The first message: "lo" On Oct. 29, 1969, a message from UCLA to Stanford Research Institute broke off after two letters of "login."

What made it an internet, a network of networks, was work begun in 1972 by Bob Kahn, joined by Vint Cerf the following year. Their design let independently run networks connect without changing how each worked inside. It was later split in two: IP for addressing and forwarding, TCP for reliability. Every ARPANET host moved to the new protocols on a single day, Jan 1, 1983.^[2]

1:21 Vint Cerf and TCP/IP Life Noggin's animated short on the protocols that let separate networks talk to one another.

The National Science Foundation's NSFNET, started in 1985, spread access through universities and required TCP/IP. Its rules confined the backbone to research and education, which encouraged private long-distance networks to grow beside it. ARPANET was shut down by about 1990, and the foundation stopped funding the NSFNET backbone in April 1995, completing the move to commercial operators. That October a U.S. federal council adopted a formal definition of the word "Internet."^[2]

The Web

The Internet and the World Wide Web are different things: the first carries data, and the second is one application running over it, a system of linked documents. Tim Berners-Lee proposed it at CERN in March 1989, and by the end of 1990 the first server and browser were running there. In early 1993 the Mosaic browser reached ordinary personal computers, and on April 30 of that year CERN released the Web's source code royalty-free, a decision that left anyone free to build on it. Known servers rose from over 500 in late 1993 to 10,000 a year later.^[3] Berners-Lee founded the World Wide Web Consortium in October 1994 to develop its standards.^[4]

4:19 The Web arrives, 20 years after email DW Shift dates the first website to 1991 and Tim Berners-Lee.

How it works

A message sent across the Internet is divided into packets, each labeled with source and destination addresses. Routers pass each packet toward its destination without any end-to-end circuit being reserved, which is what separates the design from the telephone network.^[2] TCP, running on the two end computers, gives applications a reliable, ordered stream of bytes, detecting loss with sequence numbers and resending what went missing.^[5] Applications that do not need that service can use the simpler UDP instead.^[2]

People use names, and machines use numbers. The Domain Name System, developed by Paul Mockapetris, translates one into the other through a hierarchy of servers.^[2] The original IPv4 address format allows about 4.3 billion addresses, and the central pool ran out on Feb 3, 2011, when the last five large blocks were handed to the five regional registries.^[7][8] Its successor IPv6, with 128-bit addresses, has been slow to spread. Google measured 50.1% of its traffic over IPv6 on March 28, 2026, a single-day peak, while Cloudflare Radar saw 40.1% of web requests and APNIC Labs saw 43.13% of networks capable of it.^[8]

Physically, most of the distance is covered by glass. The ITU says submarine cables carry about 99% of Internet traffic; it counted more than 500 active and planned systems as of 2024, and more than 170 repairs in 2025, nearly four a week. Fishing and anchors are the main causes of damage, ahead of earthquakes and undersea landslides.^[9]

Who runs it

No government or company owns the Internet. Its parts are run by many network operators who agree to exchange traffic, and coordination is split among several bodies. The Internet Engineering Task Force, founded in 1986, writes voluntary technical standards published as RFCs. It has no membership, decides by "rough consensus" rather than vote, and says plainly that it does not control the network.^[6] ICANN coordinates names and numbers with the regional registries; the last formal U.S. government oversight of that role ended when a contract expired on Oct 1, 2016.^[11]

Governments have argued for decades over how much say they should have. On Dec 17, 2025, the UN General Assembly's 20-year review of the World Summit on the Information Society reaffirmed the model in which governments, companies, engineers and civil society share the work, and made the Internet Governance Forum a permanent UN body.^[12]

Who is online

The ITU estimates that the online population grew by more than 240 million in 2025. Its figures also show the gaps: 94% use the Internet in high-income countries and 23% in low-income ones, 85% in cities and 58% in the countryside, 77% of men and 71% of women. Young people aged 15 to 24 lead at 82%. Coverage by 5G reaches 55% of the world's population, but 84% in high-income countries and 4% in low-income ones, and a basic mobile data plan remains unaffordable in about 60% of low- and middle-income countries.^[1] The ITU revised its earlier 2024 numbers substantially, from 5.5 billion online to 5.8 billion, so older estimates are not comparable.^[1]

Impact

By the mid-1990s browsers had turned a research tool into a commercial market, and most of what is now called online life, from retail to streaming, rests on the same protocols.^[2] The scale of two services gives a sense of it. YouTube reports more than 20 million videos uploaded daily, and Wikipedia reports nearly 15 billion page views a month.^[13][14] A newer shift is the rise of artificial intelligence, which increasingly answers questions in place of sending readers to websites; the Wikimedia Foundation has tied a drop of about 8% in human page views partly to that change.^[15]

2:13 Mosaic, Netscape and dial-up Life Noggin's short on how browsers and dial-up brought the Web to the public.

The physical footprint is substantial as well. The International Energy Agency put data centers at about 415 terawatt-hours of electricity in 2024, roughly 1.5% of the world's total, and expects that to more than double by 2030.^[16]

Controversy

Governments cut access. Access Now and its coalition counted at least 313 shutdowns in 52 countries in 2025, up from 304 the year before and the highest number since the count began, with conflict behind about 40% of them.^[10]

Network neutrality, the principle that carriers should treat all traffic alike, has been fought over for years in the United States. On Jan 2, 2025, a federal appeals court struck down the Federal Communications Commission's latest rules, holding that the agency could not regulate Internet service like a utility.^[17]

Timeline

1. July 1961 Leonard Kleinrock publishes the first paper on packet switching theory.^[2]
2. 1969 ARPANET connects its first four sites.^[2]
3. 1972 Ray Tomlinson writes basic email software, and Bob Kahn begins work on open networking.^[2]
4. Jan 1, 1983 ARPANET moves to TCP/IP.^[2]
5. 1986 The Internet Engineering Task Force is founded.^[6]
6. March 1989 Tim Berners-Lee proposes the World Wide Web at CERN.^[3]
7. April 30, 1993 CERN releases the Web's source code royalty-free.^[3]
8. April 1995 The NSFNET backbone loses federal funding, finishing its privatization.^[2]
9. Feb 3, 2011 The central pool of IPv4 addresses runs out.^[7]
10. Oct 1, 2016 The U.S. government contract over key Internet functions expires.^[11]
11. Dec 17, 2025 The UN makes the Internet Governance Forum permanent.^[12]
12. March 28, 2026 IPv6 passes half of Google's traffic for a day.^[8]