What is cartesion product?

Cartesian product of sets:- Let A and B be sets. The Cartesian product of A and B, denoted A x B (read “A cross B”) is the set of all ordered pairs (a, b), where a is in A and b is in B. For example: A = {1, 2, 3, 4, 5, 6} B = {a} A x B = {(1,a), (2,a), (3,a), (4,a), (5,a)}