Online Computer Dictionary

(After Renee Descartes, French philosper and mathematician) The Cartesian product of two sets A and B is the set A x B = a, b) | a in A, b in B}.

I.e. the product set contains all possible combinations of one element from each set. The idea can be extended to products of any number of sets.

If we consider the elements in sets A and B as points along perpendicular axes in a two-dimensional space then the elements of the product are the "Cartesian coordinates" of points in that space.