In analysis, the domain of a function is the set of values for which a function is defined. In topology, a domain is a connected, open set.

The term domain has (at least) three different meanings in mathematics. The term domain is most commonly used to describe the set of values D for which a function (map, transformation, etc.) is defined. For example, a function f(x) that is defined for real values x element R has domain R, and is sometimes said to be "a function over the reals." The set of values to which D is sent by the function is then called the range.

codomain | connected set | integral domain | map | natural domain | one-to-one | over | probability domain | range | Reinhardt domain | statistical range | surjection

high school level (California Algebra I standard)