TLD (Top Level Domain)
A TLD is the right most string in a domain name.
For example:
in "" the TLD is the ".uk" part.
the ".co" part forms the SLD (Second Level Domain) and is described further in SLDs
TLDs are split into two groups:

1. gTLDs (generic top-level domain).

These are used by specific industry types. In short the extension is a rough abbreviation of the industry for example:

  • .biz
  • - for business use
  • .cat
  • - for Catalan language/culture
  • .com
  • - for commercial organizations, but unrestricted
  • .edu
  • - for post-secondary educational establishments
  • .gov
  • - for governments and their agencies in the United States
  • .info
  • - for informational sites, but unrestricted
  • .int
  • - for international organizations established by treaty
  • .jobs
  • - for employment-related sites
  • .mil
  • - for the US military
  • .mobi
  • - for sites catering to mobile devices
  • .name
  • - for families and individuals
  • .net
  • - originally for network infrastructures, now unrestricted
  • .org
  • - originally for organisations not clearly falling within the other gTLDs, now unrestricted

    2. sponsored TLDs.

    These are TLDs proposed by agencies to represent specific ‘communities’ on the internet. Approved sponsored TLDs are governed by the awarded agency who enforce the rules which restric the use of the respective tlds to organisations within the specific criteria.

    Examples of sponsored TLDs are:
  • .aero
  • - members of the air-transport industry
    Société Internationale de Télécommunications Aéronautiques.
  • .coop
  • - cooperative associations
    Dot Cooperation LLC
  • .museum
  • - museums
    Museum Domain Management Association
  • .pro
  • - credentialed professionals and related entities
    Registry Services Corporation
  • .travel
  • - travel agents, airlines, hoteliers, tourism bureaus, etc.
    The Travel Partnership
  • .tel
  • - for services involving connections between the telephone network and the Internet (added March 2, 2007)
    Telname Limited

    An example of an industry with a relatively new sponsored TLD is the .travel tld reserved for the travel industry – detail about the .travel TLD can be found at The Tralliance Corporation website.

    Country Specific TLDs
    TLDs with two letters are country specific tld’s.
    A full list of country specific TLD’s can be found on the iana (Internet Assigned Numbers Authority) website

    Over recent years many new TLDs have been introduced to the internet including .tv, .biz, .aero and many more.
    For more information on new TLDs visit InterNIC FAQs on New Top-Level Domains