[2] It serves 18 million users and is the busiest National Research and Education Network in Europe by volume of data carried.

The network is linked to other European and worldwide NRENs through GÉANT and peers extensively with other ISPs at Internet Exchange Points in the UK.

[8][9] A number of national computer facilities serving the Science Research Council (SRC) community developed in the early 1970s, each with their own star network (ULCC London, UMRCC Manchester, Rutherford Appleton Laboratory).

[8] Other regional networks followed in the mid-late 1970s around Edinburgh (RCOnet), London (METROnet), the Midlands (MIDnet), and Newcastle (NUMAC - the Northern Universities Multiple Access Computer[10]) among others such as Yorkshire and the South East.

[8][11][12] In the early 1980s a standardisation and interconnection effort started, hosted on an expansion of the SERCnet X.25 research network.

[nb 1][13][14][15] The JANET effort was based on the Coloured Book protocols developed by the British academic community, which provided the first complete X.25 standard,[16][17] and gave the UK "several years lead over other countries".

By then, the UK had a pre-existing national standard, which was retained as the .uk Internet country-code top level domain for the United Kingdom.

[18] It was set up as a pilot project in March 1991 to host Internet Protocol (IP) traffic on the existing network.

A further upgrade in the early 1990s took the backbone to 8 Mbit/s and the access links to 2 Mbit/s, making Janet the fastest X.25 network in the world at the time.

The core point of presence (Backbone) sites in SuperJanet4 were Edinburgh, Glasgow, Warrington, Reading, Bristol, Portsmouth, London and Leeds.

It is designed not only to fully accommodate the requirements of the traditional JANET user base - all research institutes, universities and further education - but also to meet the needs of a new userbase in the UK's primary and secondary schools.

[27] Janet6 started to go live in July 2013,[28] and was officially launched at an event at the London Film Museum on 26 November 2013.