domain

On the Internet, segment of an address that specifies an organization, its type, or its country of origin. All countries except the USA use a final two-letter code such as ca for Canada and uk for the UK. A us suffix exists for the USA, but is not widely used. US addresses usually end in one of seven ‘top-level’ domains, which specify the type of organization: com (commercial), mil (military), org (usually a nonprofit-making organization), and so on. In 2006 there were more than 80 million domain names registered on the Internet.

The domain names are for the benefit of humans; to enable mail and other messages to be sorted by machine, computers use IP (Internet protocol) numbers. To route a message, the computer looks up the domain name on a domain name server (DNS), which tells the computer the number.

In 1999, the US Government handed over responsibility for the top-level domain names com, org, and net from the private company Network Solutions Inc (NSI) to the non-commercial organization ICANN.