internetwork

Internet is a shortening of internetwork or internetworking, a term from computer engineering referring to a network of networks — a system that connects multiple separate computer networks into a larger whole. The prefix inter-, from Latin inter ('between, among'), had been productively used in English for centuries (international, interracial, interview), and its application to networking was precise: the internet was not a single network but a protocol for connecting different networks, allowing them to communicate regardless of their internal architecture. The foundational technology, ARPANET, was funded by the U.S. Defense Department's Advanced Research Projects Agency beginning in 1969, with the explicit goal of creating a communications system that could survive nuclear attack by routing information around damaged nodes. The internet was, at its origin, a military resilience project.

The key conceptual innovation was packet switching, developed independently by Paul Baran at RAND Corporation and Donald Davies at the National Physical Laboratory in Britain. Instead of sending a message along a single dedicated circuit (as telephone systems did), packet switching breaks information into discrete packets, each labeled with its destination, and routes them independently through whatever network paths are available. The packets reassemble at the destination. This meant that the failure of any single route or node would not interrupt transmission — the packets would simply find another path. The internet's decentralized architecture, which still mystifies those who look for its physical center, was designed specifically to have no center vulnerable to attack.

The word 'internet' (lowercase, with the article 'the') began appearing in the early 1980s as TCP/IP — the Transmission Control Protocol and Internet Protocol — standardized the rules by which different networks could communicate. The World Wide Web, invented by Tim Berners-Lee at CERN in 1989, built a system of hyperlinked documents on top of the internet, creating the browsable information space that most people experience as the internet itself. The two are not identical: the internet is the network infrastructure; the web is one service running on it. But the distinction has been largely lost in popular usage, where 'internet' and 'web' have become interchangeable. Berners-Lee's invention made the military network into a publishing medium, and the publishing medium became the world's nervous system.

The internet's growth from 1990 to the present constitutes the fastest adoption of any communication technology in history, surpassing the telephone, radio, and television in the speed of its spread. Four billion people now use it. It hosts commerce, government, medicine, journalism, entertainment, warfare, and the private communications of individuals in every country. It has been, depending on who is analyzing it, the greatest democratizing force in history (the Arab Spring) and the greatest centralizing force (three companies controlling global search, social media, and cloud infrastructure). The word that named a military resilience project now names the most consequential infrastructure human beings have ever built.