In mathematics, the arrow \(\mapsto\) (which in is called “\mapsto”) is used to describe what a function does to an arbitrary input. It is commonly used in combination with colon-to notation, which describes what a function’s domain and codomain are.
By itself, \(\mapsto\) can be used to describe a function without naming it, and so is a way to describe in mathematics.
The function \(f(x) = x^2\) from the real numbers to the real numbers can be described using a combination of colon-to notation and mapsto notation as
In one line, although this is less common,
(see in notation).