1. Invention of packet switching
1961 to 1964NetworkingInventionEvent page
Existing telecommunications relied on circuit switching, where a dedicated physical path was established for each call. This approach was inefficient for computer data, which arrives in bursts, and vulnerable to single points of failure. A nuclear attack could disable entire communication networks by destroying key switching centres.
Packet switching divided data into small, independently-routed packets that could take different paths through a network and be reassembled at the destination. This made networks more efficient for bursty computer traffic and more resilient to failures.
Leonard Kleinrock at MIT developed the mathematical theory of packet switching in his 1961 PhD work. Independently, Paul Baran at RAND Corporation designed distributed packet-switched networks for military survivability in 1964. In the UK, Donald Davies at NPL coined the term "packet" and designed similar systems in 1965-66. These parallel developments converged to form the foundation of modern networking.1, 2, 3, 4
2. ARPANET's first message
29 October 1969NetworkingProtocol deployedEvent page
Despite theoretical work on packet switching, no operational packet-switched computer network existed. Researchers at different institutions could not easily share computing resources or communicate electronically.
The first host-to-host message was sent over ARPANET from UCLA to Stanford Research Institute. This demonstrated that packet switching worked in practice and marked the beginning of the internet.
ARPA (Advanced Research Projects Agency) funded the development of a packet-switched network connecting university research computers. The first Interface Message Processor (IMP) was installed at UCLA on 30 August 1969. On 29 October 1969, Charley Kline at UCLA attempted to log into the SRI computer. The system crashed after transmitting 'LO' (the first two letters of 'LOGIN'), but the connection was successfully re-established.5, 4
3. TCP/IP specification
May 1974 to September 1981NetworkingStandard publishedEvent page
ARPANET used the Network Control Protocol (NCP), which worked only within a single network. There was no way to interconnect different networks (e.g., ARPANET, satellite networks, radio networks) into a unified internetwork.
The Transmission Control Protocol (TCP) and Internet Protocol (IP) provided a universal protocol suite that could interconnect heterogeneous networks. IP handled routing between networks; TCP handled reliable end-to-end communication.
Vinton Cerf and Robert Kahn published 'A Protocol for Packet Network Intercommunication' in May 1974, describing the initial TCP design. RFC 675 (December 1974) provided the first TCP specification. The protocol was later split into TCP (transport) and IP (network), formalised in RFC 791 (IP) and RFC 793 (TCP) in September 1981.6, 7, 8, 9, 4
4. Domain Name System
November 1983NetworkingStandard publishedEvent page
The early internet used a single HOSTS.TXT file maintained by SRI-NIC to map hostnames to IP addresses. As the network grew, this centralised approach became unsustainable. Updates were slow, the file grew unwieldy, and there was no hierarchy for organising names.
The Domain Name System (DNS) replaced the flat HOSTS.TXT file with a distributed, hierarchical naming system. DNS introduced domain names (like example.com), delegated authority through a tree structure, and allowed names to be resolved through a network of nameservers.
Paul Mockapetris at USC's Information Sciences Institute designed DNS and published the specification in RFC 882 and RFC 883 in November 1983. The design introduced the concept of zones, authoritative nameservers, and recursive resolution. RFCs 1034 and 1035 (1987) refined the specification and remain the foundational DNS documents.10, 11, 12, 13
5. World Wide Web
March 1989 to August 1991NetworkingInventionEvent page
Information at CERN was scattered across different systems, formats, and machines. Researchers struggled to share documents and data. Existing hypertext systems were isolated and did not work across networks. The internet existed but lacked a user-friendly way to navigate information.
Tim Berners-Lee invented the World Wide Web: a system combining hypertext with internet protocols. The Web introduced URLs (addresses), HTTP (transfer protocol), and HTML (document format). For the first time, anyone could publish and link to information accessible worldwide.
Tim Berners-Lee proposed a 'distributed hypertext system' at CERN in March 1989. Working with Robert Cailliau, he developed the first web server (httpd), browser (WorldWideWeb), and HTML by late 1990. The first website (info.cern.ch) went live on 6 August 1991. CERN released the software into the public domain in April 1993.14, 15
6. HTTP, 0.9 to RFC 9110
May 1996 to June 2022NetworkingStandard publishedEvent page
The original HTTP/0.9 was extremely simple, supporting only GET requests for HTML. As the Web grew, limitations became apparent: no persistent connections (new TCP connection for each request), no content negotiation, no caching headers, and no security.
HTTP evolved through multiple versions: HTTP/1.0 (1996) added headers, methods, and status codes; HTTP/1.1 (1999) added persistent connections and chunked transfer; HTTP/2 (2015) added multiplexing and header compression; HTTP/3 (2022) moved to QUIC, eliminating TCP head-of-line blocking.
RFC 1945 formalised HTTP/1.0 in 1996. RFC 2616 (HTTP/1.1) addressed performance with persistent connections. Google's SPDY research influenced HTTP/2 (RFC 7540). Cloudflare and Google championed QUIC, leading to HTTP/3 (RFC 9114). Each version maintained backward compatibility while addressing specific performance bottlenecks.16, 17, 18, 19, 20