The unique name that identifies an Internet site. Domain Names always has 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general.
A given machine may have more than one Domain Name but a given Domain Name points to only one machine. For example, the domain names: yahoo.com mail.yahoo.com workshop.yahoo.com can all refer to the same machine, but each domain name can refer to no more than one machine. Usually, all of the machines on a given Network will have the same thing as the right-hand portion of their Domain Names (yahoo.com in the examples above).
It is also possible for a Domain Name to exist but not be connected to an actual machine. This is often done so that a group or business can have an Internet e-mail address without having to establish a real Internet site. In these cases, some real Internet machine must handle the mail on behalf of the listed Domain Name.