| Introduced | 24 July 1985 |
|---|---|
| TLD type | Country code top-level domain |
| Status | Unused (reserved) |
| Registry | JANET (Jisc) |
| Intended use | Entities connected with Great Britain (the United Kingdom) |
| Actual use | Fallen into disuse in favour of .uk |
| Registration restrictions | No registrations presently being taken |
| Structure | name.gb, Government Websites assigned as .hmg.gb |
.gb is a reserved Internet country code top-level domain (ccTLD) for the United Kingdom, derived from Great Britain.
The domain was introduced with RFC 920 [1] in October 1984 that set out the creation of ccTLD generally using country codes derived from the corresponding two-letter code in the ISO 3166-1 list. However, the .uk domain had been created separately a few months before the compilation of this list. [2] Consequently, .gb was never widely used. It is no longer possible to register under this domain.
.gb was used for a number of years, mainly by British government organisations and commercial e-mail services using X.400-based e-mail infrastructure. This simplified translating between DNS domains and X.400 addresses, which used "GB" as a country code. [3]
With the demise of X.400 e-mail and IANA's general aim of one TLD per country, use of .gb declined; the domain remains in existence, but it is not currently open to new domain registrations.
As of 2025, there are at least three subdomains resolving through DNS (although none serve a web page or use): hermes.dra.hmg.gb, delos.dra.hmg.gb, and dfhnet.dra.hmg.gb. [4] They were originally owned by the Defence Research Agency, [5] which became the Defence Evaluation and Research Agency in 1995 and was split into QinetiQ and the Defence Science and Technology Laboratory in 2001; the websites became defunct some time thereafter. [6]
As of November 2022 [update] , Central Digital and Data Office's intention was to inform ICANN early in 2023 that the UK wishes to retire the .gb ccTLD. [7] [ needs update ]