.uk is the Internet country code top-level domain (ccTLD) for the United Kingdom.

The use of .uk rather than .gb for the top-level domain is due to its pre-existing use in the (now obsolete) JANET Name Registration Scheme in which the order of address components were reversed. .uk was made available in DNS to simplify the translation to and from these addresses. There were plans to eventually transition to .gb, but this never occurred and the use of .uk is now entrenched.

As with other ccTLDs in the early days it was originally delegated to an individual by Jon Postel. In time, it passed to the relevant project manager (Dr Willie Black ) at the UK Education and Research Networking Association (UKERNA). The actual allocation of domain names was operated by the UK Naming Committee which was in practice a mailing list of representatives of all organisations involved in the UK Internet system at the time. By the mid-1990s it was becoming clear that the growth of the Internet, and particularly the advent of the World Wide Web was pushing requests for domain name registrations up to levels that were not manageable by a group of part-time voluntary managers. Various plans were put forward for the possible management of the domain and in response to this Dr Black, as the .uk Name, decided that the way forward was to establish a neutral, not-for-profit commercial entity to deal with the .uk domain properly. This received widespread support and Nominet UK was formed to be the .uk Network Information Centre, a role which it continues to this day.

The general form of the rules (i.e. which domains can be registered and whether to allow second level domains) was set by the Naming Committee, and Nominet UK has not introduced major changes.

It is prohibited to register a domain name directly under .uk (such as .example.uk) and a second-level domain must be used (such as example.co.uk).

However, some domains delegated before the creation of Nominet UK remain. Examples include parliament.uk (Parliament), bl.uk and british-library.uk (the British Library), nls.uk (the National Library of Scotland) and jet.uk (UKAEA as operator of the Joint European Torus experimental fusion tokamak). No new 'normal' registrations at the second level are accepted although there is a system for allocating new second level domains to expand the capacity of the system. Such allocations are rarely made.

Second-level domains

• .ac.uk - academic (tertiary education; primary and secondary use .sch.uk)
• .co.uk - commercial/general
• .gov.uk - government
• .ltd.uk - limited companies
• .me.uk - personal
• .mod.uk - Ministry of Defence establishments
• .net.uk - ISPs and network companies
• .nic.uk - network use only
• .nhs.uk - National Health Service institutions
• .org.uk - non-profit organisations
• .plc.uk - public limited companies
• .police.uk - police forces
• .sch.uk - schools

Individual institutions

• .bl.uk and .british-library.uk - British Library
• .icnet.uk - Imperial Cancer Research Fund
• .jet.uk - Joint European Torus
• .nel.uk - National Engineering Laboratory
• .nls.uk and .national-library-scotland.uk - National Library of Scotland
• .parliament.uk - Parliament of the United Kingdom

Inactive

• .govt.uk - former government domain, now deleted and replaced by .gov.uk
• .lea.uk - local education authorities; since fallen out of use.
• .orgn.uk - former non-profit organisations domain; virtually obsolete and replaced by .org.uk

.co.uk, .ltd.uk, .me.uk, net.uk, .nic.uk, .org.uk, .plc.uk and .sch.uk are managed by Nominet UK and are generally (except .nic.uk) available for registration by the public (though they all carry various degrees of restrictions). The other second-level domains are managed by various government agencies.

Allocations are on a strict first-come, first-served basis to qualified applicants. There are no territorial restrictions: applicants need not have any connection to the UK.

See also

• .gb

External links

• IANA .uk whois information
• .uk registry website