Computer network

The first computer network that became the Internet was born on October 29, 1969, at 10:30 p.m., when a graduate student at UCLA typed 'login' to connect to a computer at Stanford Research Institute. The system crashed after two characters. The first message ever sent across ARPANET was 'lo'—the beginning of a transformation that would connect billions of humans.

The adjacent possible had been assembling since the early 1960s. In 1962, J.C.R. Licklider at ARPA (the Advanced Research Projects Agency) envisioned what he called the 'Galactic Network'—a globally interconnected set of computers where anyone could access data and programs from any site. Licklider's memo planted the seed. Bob Taylor, who succeeded him, initiated the ARPANET project in 1966 to enable resource sharing between remote computers.

The critical innovation was packet switching—breaking data into small packets that travel independently across the network and reassemble at the destination. Leonard Kleinrock at UCLA developed the mathematical theory. Paul Baran at RAND and Donald Davies in Britain independently conceived similar approaches. The convergent emergence of packet switching on three continents proved the adjacent possible had opened.

In 1969, ARPA awarded Bolt Beranek & Newman (BBN) the contract to build the Interface Message Processors (IMPs)—the routing computers that would form the network's backbone. Bob Kahn developed the first protocols. On September 2, 1969, BBN installed the first IMP at UCLA's Network Measurement Center. Charley Kline sent that first crashed message to SRI six weeks later.

By December 5, 1969, the initial four-node network was operational: UCLA, Stanford Research Institute, UC Santa Barbara, and the University of Utah. Email followed in 1971. File transfer protocols emerged. By 1973, ARPANET had nodes in Britain and Norway—the first international connections.

The pivotal moment came on January 1, 1983, when ARPANET adopted TCP/IP—the protocols created by Vint Cerf and Bob Kahn that allowed different networks to communicate. This 'flag day' transition created the Internet as a network of networks. ARPANET itself was decommissioned in 1990, its mission accomplished: it had proven that packet-switched computer networks were possible and useful.

The cascade from that 'lo' message now connects half of humanity. Social networks, cloud computing, e-commerce, streaming media—everything built on the Internet traces back to those four nodes and the crashed login attempt at UCLA.