# Function (mathematics)

> A function from a set $X$ to a set $Y$ assigns to each element of $X$ exactly one element of $Y$. The set $X$ is called the domain of the function and the set $Y$ is called the codomain of the function.

A function from a set $X$ to a set $Y$ assigns to each element of $X$ exactly one element of $Y$. The set $X$ is called the domain of the function and the set $Y$ is called the codomain of the function.

A function $f$ from a set $X$ to a set $Y$ is denoted as $f: X \rightarrow Y$.