<networking> The last and most significant component of an Internet fully qualified domain name, the part after the last ".". For example, host wombat.doc.ic.ac.uk is in top-level domain "uk" (for United Kingdom). Every other country has its own top-level domain, including ".us" for the U.S.A. Within the .us domain, there are subdomains for the fifty states, each generally with a name identical to the state's postal abbreviation. These are rarely used however. Within the .uk domain, there is a .ac.uk subdomain for academic sites and a .co.uk domain for commercial ones. Other top-level domains may be divided up in similar ways. In the US and some other countries, the following top-level domains are used much more widely than the country code: .com - commercial bodies .edu - educational institutions .gov - U. S. government .mil - U. S. armed services .net - network operators .org - other organisations Since the rapid commercialisation of the Internet in the 1990s the ".com" domain has become particularly heavily populated with every company trying to register its company name as a subdomain of .com, e.g. "netscape.com" so as to make it easy for customers to guess or remember the URL of the comany's home page. United Nations entities use the domain names of the countries where they are located. The UN headquarters facility in New York City, for example, is un.org. Several new top-level domains are about to be added (Oct 1997): .nom - individual people .rec - recreational organisations .firm - businesses such as law, accounting, engineering .store - commercial retail companies .ent - entertainment facilities and organisations (1997-10-08)

Top Level DOMAIN (Reference: Internet, ICANN)

top-level domain

A pseudo-top-level domain is a label or name for a computer network that is not participating in the world-wide official Domain Name System and may not even participate in the Internet, but may use a similar domain name hierarchy. Historically the best known large networks in this group were .

A geographic top-level domain (often shortened as geographic TLD or geoTLD) is any of an unofficial group of top-level domains in the Domain Name System of the Internet using the name of or invoking an association with a geographical, geopolitical, ethnic, linguistic or cultural community. The IANA does not recognize these domains as their own group within the Root Zone Database, rather classifying them as generic top-level domains.

Generic top-level domains (gTLDs) are one of the categories of top-level domains (TLDs) maintained by the Internet Assigned Numbers Authority (IANA) for use in the Domain Name System of the Internet. A top-level domain is the last level of every fully qualified domain name.

A sponsored top-level domain (sTLD) is one of the categories of top-level domains (TLDs) maintained by the Internet Assigned Numbers Authority (IANA) for use in the Domain Name System of the Internet, alongside country-code top-level domains (ccTLD) and generic top-level domains (gTLD) .

A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs.

An internationalized country code top-level domain is a top-level domain in the Domain Name System (DNS) of the Internet. IDN ccTLDs are specially encoded domain names that are displayed in an end user application, such as a web browser, in their language-native script or alphabet, such as the Arabic alphabet, or a non-alphabetic writing system, such as Chinese characters.

The Council of European National Top-Level Domain Registries (CENTR) is an organization established to act as a peak body of top-level domain name registries.