The rule is that any number raised to the power of 0 equals to 1.
So if 2 or 1,000,000 is raised to the power of 0 it equals 1.
But 0 to the power 0 is undefined!
0 to any positive power is 0, so 0 to the power 0 should be 0. But any positive number to the power 0 is 1, so 0 to the power 0 should be 1. We can't have it both ways. Underlying this argument is the same idea as was used in the attempt to define 0 divided by 0.