Parity is a mathematical term that describes the property of an integer's inclusion in one of two categories: even or odd. An integer is even if it is 'evenly divisible' by two and odd if it is not even. For example, 6 is even because there is no remainder when dividing it by 2. By contrast, 3, 5, 7, 21 leave a remainder of 1 when divided by 2. Examples of even numbers include -4, 0, 8, and 1738. In particular, zero is an even number. Some examples of odd numbers are -5, 3, 9, and 73. Parity does not apply to non-integer numbers.