A Cartesian product is a mathematical operation that returns a set (or product set or simply product) from multiple sets.

That is, for sets A and B, the Cartesian product A × B is the set of all ordered pairs (a, b) where a ∈ A and b ∈ B.

Products can be specified using set-builder notation, e.g.

A x B = {(a, b) | a∈ A and b∈B}