The history of internet starts with the computer network launched by the ARPA (Advanced Research Projects Agency) Group of the U.S. Department of Defense in 1969. But at that time ARPA network was not the only one, there were other similar initiatives. However, mainstream historians only remember ARPA and the others have been forgotten.

The development of the TCP / IP protocol only began in 1973, and at least 20 different network technologies have been developed before the adoption of the X25 standard of the packet-switched networks in 1973. The history of such networks can be divided into three eras: the pre-X25 periods, the years of X25 and the internet era switching from X25 to the IP when restrictions on connection gradually disappeared.

The first period was defined by the following networks.

Besides ARPANET, the two other important initiatives from America were Telenet and Tymnet. The Canadian BNRNET was a network which Bell Northern Research developed for internal use. It initially had only one host but was designed to support many hosts.

In the early 1970s, the experimental CYCLADES was developed to explore alternatives to the ARPANET design. It operated until 1981, its main achievement was that it had reduced the original complexity of packet switching. RCP, the other French network, in contrast to CYCLADES, emphasised terminal to host and terminal to terminal connection instead of the communication between hosts.

The Nippon PTT DDX 1 and 2 was the mix of circuit and packet switching, while the European COST II linked several national networks and became operational in 1976. The EPSS was an experiment of the UK Post Office. The other British internet project of the era was the NPL.

The program of General Electric GEIS (General Electric Information Services) launched in 1965, was one of the most significant experiment of the epoch. IPSANET operated between 1976 and 1993 and it main achievement was the development of an early e-mail service.

Famous companies and institutions as well as national phone companies also were experimenting with networks: OCTOPUS (Lawrence Livermore National Laboratory), PUP and XNS (Xerox PARC), Philips Research, SNA (IBM), Rand Institue, SCANNET (Nordic), RETD (Compa?ía Telefónica Nacional de Espa?a) etc..