# Cartesian product

The Cartesian product of two sets A and B is the set (usually denoted by A × B) consisting of all ordered pairs (a, b) where $a \in A$ and $b \in B$. The Cartesian product is named after René Descartes, who invented this concept.
A common example of a Cartesian product is the coordinate plane, $\mathbb{R}^2$. This is all ordered pairs (a,b) of real numbers a and b. It is used for graphing functions on the real numbers.