hey guys, was wondering if someone could tell me what this would be represented as in a cayley table? (Z being the set of integers)

$\displaystyle Z/2Z \times Z/2Z$

i know that $\displaystyle Z/2Z = \{0,1\}$, and $\displaystyle (Z/2Z)^{\times} = \{0,1\}$, but i dont know what $\displaystyle Z/2Z \times Z/2Z$ is!!

thanks heaps (in advance)