Top-level domain

A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet after the root domain. The top-level domain names are installed in the root zone of the name space. For all domains in lower levels, it is the last part of the domain name, that is, the last non empty label of a fully qualified domain name. For example, in the domain name www.example.com, the top-level domain is .com. Responsibility for management of most top-level domains is delegated to specific organizations by the ICANN, an Internet multi-stakeholder community, which operates the Internet Assigned Numbers Authority (IANA), and is in charge of maintaining the DNS root zone. Originally, the top-level domain space was organized into three main groups: Countries, Categories, and Multiorganizations. An additional temporary group consisted of only the initial DNS domain, .arpa, and was intended for transitional purposes toward the stabilization of the domain name system. IANA distinguishes the following groups of top-level domains: Infrastructure top-level domain (ARPA): This group consists of one domain, the Address and Routing Parameter Area. It is managed by IANA on behalf of the Internet Engineering Task Force for various purposes specified in the Request for Comments publications. Generic top-level domains (gTLD): Top-level domains with three or more characters Generic restricted top-level domains (grTLD): These domains are managed under official ICANN accredited registrars. Sponsored top-level domains (sTLD): These domains are proposed and sponsored by private agencies or organizations that establish and enforce rules restricting the eligibility to use the TLD. Use is based on community theme concepts; these domains are managed under official ICANN accredited registrars. country-code top-level domains (ccTLD): Two-letter domains established for countries or territories. With some historical exceptions, the code for any territory is the same as its two-letter ISO 3166 code.