The set of ordered pairs $(a, b)$ where $a \in A$ and $b \in B$:
$$A \times B = \{(a, b) \ \vert \ a \in A \lor b \in B\}$$Basically all of the arrangements that can be made with items in a set.
The set of ordered pairs $(a, b)$ where $a \in A$ and $b \in B$:
$$A \times B = \{(a, b) \ \vert \ a \in A \lor b \in B\}$$Basically all of the arrangements that can be made with items in a set.