An exponent tells the problem solver how many times to multiply a number by itself; therefore, a zero exponent tells the problem solver to multiply the number zero times by itself. Basically, any number with a zero exponent is equal to one, unless the base number is zero.
Essentially, an exponent that is zero is equal to a variable to the power of an exponent times a variable to the negative power of the same exponent. For instance, x2 times x-2 is equal to x2 divided by x-2. Any number divided by itself is equal to one.
Zero to the power of zero is a special case, however. Some mathematicians say that it equals one, while others say that it equals zero.