Domain

A domain name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet. Domain names are used in various networking contexts and for application-specific naming and addressing purposes. In general, a domain name identifies a network domain, or it represents an Internet Protocol resource, such as a personal computer used to access the Internet, a server computer hosting a website, or the web site itself or any other service communicated via the Internet.
Any name registered in the DNS is a domain name. The first-level set of domain names are the top-level domains, including the generic top-level domains, such as the prominent domains com, info, net, edu, and org, and the country code top-level domains.