A domain name identifies an organization or entity on the Internet.
For instance, the domain name "www.exabytes.com" points to an Internet address for "Exabytes.com" at IP address 199.0.0.2 and a specific host server known as "www". The "com" portion of the domain name indicates the nature of the organization or entity (in this case, "commercial") and is referred to as the top-level domain name.
The "exabytes" section of the domain name designates the organization or entity, and when combined with the top-level, is termed the second-level domain name. The second-level domain name corresponds to and can be viewed as the "readable" representation of the Internet address.
A third level can be established to specify a certain host server at the Internet address. In this example, "www" is the name of the server that processes Internet requests. (Another server could be designated as "www2".) A third level of the domain name is optional. For instance, the fully-qualified domain name could simply be "exabytes.com" with the server inferred.
Subdomain levels can also be utilized. For example, one could have "www.server.exabytes.com".
Together, "www.exabytes.com" forms a fully-qualified domain name.
Second-level domain names must be unique across the Internet and must be registered with one of the ICANN-accredited registrars for the COM, NET, and ORG top-level domains. When applicable, a top-level domain name may be geographic. (At present, most non-U.S. domain names use a top-level domain associated with the country of the server.)
To register a U.S. geographic domain name or a domain name under a country code, consult an appropriate registrar.
On the Web, the domain name is the segment of the Uniform Resource Locator (URL) that informs a domain name server using the domain name server (DNS) whether and where to redirect requests for a Web page. The domain name is associated with an IP address (which signifies a physical location on the Internet).
Multiple domain names can be linked to the same Internet address. This enables various individuals, businesses, and organizations to maintain distinct Internet identities while utilizing the same Internet server.