The history of the Internet dates back to the early development of communication networks. The idea of a computer network intended to allow general communication among users of various computers has developed through a large number of stages. The melting pot of developments brought together the network of networks that we know as the Internet. This included both technological developments and the merging together of existing network infrastructure and telecommunication systems.

The infrastructure of the Internet spread across the globe to create the world wide network of computers we know today. It spread throughout the Western countries before entering the developing countries, thus creating both unprecedented worldwide access to information and communications and a digital divide in access to this new infrastructure. The Internet went on to fundamentally alter the world economy, including the economic implications of the dot-com bubble.

In the fifties and early sixties, prior to the widespread inter-networking that led to the Internet, most communication networks were limited by their nature to only allow communications between the stations on the network. Some networks had gateways or bridges between them, but these bridges were often limited or built specifically for a single use. One prevalent computer networking method was based on the central mainframe method, simply allowing its terminals to be connected via long leased lines. This method was used in the 1950s by Project RAND to support researchers such as Herbert Simon, in Pittsburgh, Pennsylvania, when collaborating across the continent with researchers in Santa Monica, California, on automated theorem proving and artificial intelligence.

Later on a scientist named Robert Taylor intended to realize Licklider's ideas of an interconnected networking system. Bringing in Larry Roberts from MIT, he initiated a project to build such a network. The first ARPANET link was established between the University of California, Los Angeles and the Stanford Research Institute on 21 November 1969. By 5 December 1969, a 4-node network was connected by adding the University of Utah and the University of California, Santa Barbara. Building on ideas developed in ALOHA net, the ARPANET started in 1972 and was growing rapidly. By 1981 the number of hosts had grown to 213, with a new host being added approximately every twenty days.

ARPANET became the technical core of what would become the Internet, and a primary tool in developing the technologies used. ARPANET development was centred around the Request for Comments (RFC) process, still used today for proposing and distributing Internet Protocols and Systems.

The term "Internet" was adopted in the first RFC published on the TCP protocol (Transmission Control Protocol). It was around the time when ARPANET was interlinked with NSFNet that the term Internet came into more general use, with "an internet" meaning any network using TCP/IP. "The Internet" came to mean a global and large network using TCP/IP, which at the time meant NSFNet and ARPANET. Previously "internet" and "internetwork" had been used interchangeably, and "internet protocol" had been used to refer to other networking systems such as Xerox Network Services.