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In the Domain Name System (DNS), the highest level of the hierarchy is the top-level domain (TLD) — that portion of the domain name that appears furthest to the right.


There are two kinds of TLDs: generic TLDs (gTLDs) and country-code TLDs (ccTLDs):

  • gTLDs are a specific set of domain names, including: ".com", ".net", and ".org" as well as others such as ".museum", ".info" and ".gov".[1] The gTLDs initially denoted the intended function of that portion of the domain space. For example, ".com" was established for commercial users, ".org" for not-for-profit organizations, and ".net" for network service providers.
  • ccTLDs, are top level domain names divided by country, using a standard list.[2] There is no top-level designation for the United States because the assignment of names and numbers for the internet was first contracted there.

There are currently 20 gTLDs and 248 ccTLDs.

Domain management[]

Each top-level domain has a designated administrator, called a domain name registry, which is the entity responsible for managing and setting policy for that domain.

Because TLDs are the most general level of organization for Internet addresses, the administrators of TLDs represent the gatekeepers that individuals or businesses must satisfy in order to obtain the rights to use a specific Internet address. For example, one seeking to register the website "" must go to the administrator of the ".com" TLD to determine the availability of that Internet address and then, if it is available, satisfy the administrator's registration criteria in order to obtain the right to use that address.

TLDs are primarily controlled and administered by private entities. However, there is a series of country-specific TLDs, each of which is controlled by the corresponding government. The United States controls and administers the ".us" TLD through the NTIA.[3]


  1. See Internet Assigned Numbers Authority, Generic Top Level Domains (full-text).
  2. See IANA, Root-Zone Whois Index by TLD Code (A full list of ccTLDs and their administrators).
  3. Peterson v. National Telecomm. & Infor. Admin., 478 F.3d 626, 629-30 (4th Cir. 2007) (full-text).