Domain has several meanings:

• some kind of territory, such as (for example) a demesne or a realm
• synonymous with field, e.g. the domain of computer science
• public domain, a body of works and knowledge without proprietary interest
• domain of discourse in symbolic logic
• eminent domain, the power of government to confiscate private property for public use
• in biology, a domain is a subdivision even larger than a kingdom
• in biochemistry and protein science, a domain is an autonomously folding functional module of a protein
• in physics a domain is a region of a solid inside which a property is uniform (for example magnetic domain in ferromagnetism)
• application domain , the kind of uses a computer program or something else is used for
• domain name, as used by a URL or Uniform Resource Locator.

Information technology

In information technology domains can occur as:

• a broadcast domain in computer networking
• a domain name, part of the name of a machine on the Internet
  • a Windows Server domain, a centrally-managed group of computers using the Windows operating system

Mathematics

In mathematics domain can refer to:

• the domain of a function
• an ordered structure studied in domain theory
• an integral domain and Euclidean domain, types of ring
• a set that is open and connected

Etymology

The original etymological implication of the word domain carries the idea of something ruled. Compare dominion.