A computer term for the following: 1) Highest subdivision of the Internet, for the most part by country (except in the U.S., where it's by type of organization, such as educational, commercial, and government). Usually the last part of a host name; for example, the domain part of ibm.com is .com, which represents the domain of commercial sites in the U.S. 2) In corporate data networks, a group of client computers controlled by a server system.