Klein group

The Klein group is a mathematical group defined by consisting of 4 elements each of one, but the identity, has order 2. It is abelian, and isomorphic to C₂ × C₂, the direct product of two copies of the [cyclic group]? of order 2.

It has the following multiplication table:

o	I	a	b	ab
I	I	a	b	ab
a	a	I	ab	b
b	b	ab	I	a
ab	ab	b	a	I