**Domain** has several meanings:

- some kind of territory
- 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
- broadcast domain in computer networking
- software domain in software engineering, a software area that contains systems sharing commonalities and variabilities.
- domain name, part of the name of a machine on the Internet
- in mathematics a domain can be
- the domain of a mathematical function
- an ordered structure studied in domain theory
- an integral domain and Euclidean domain, types of mathematical ring

- in biology, a domain is a subdivision even larger than a kingdom
- in biochemistry and protein science, a domain is a autonomously folding functional module of a protein