In mathematics, a function space is a set of functions between two fixed sets. Often, the domain and/or codomain will have additional structure which is inherited by the function space. For example, the set of functions from any set X into a vector space has a natural vector space structure given by pointwise addition and scalar multiplication. In other scenarios, the function space might inherit a topological or metric structure, hence the name function space.

Let V be a vector space over a field F and let X be any set. The functions X → V can be given the structure of a vector space over F where the operations are defined pointwise, that is, for any f, g : X → V, any x in X, and any c in F, define