**The only difference between the set of positive integers and the set of nonnegative integers is the inclusion of zero in the set of nonnegative integers.** Zero is neither a positive number nor a negative number. It is considered a rational number, an even number and a real number.

The set of negative integers can be written as {..., -5, -4, -3, -2, -1}, while the set of positive integers can be written as {1, 2, 3, 4, 5, ...}. To include zero, the set of nonnegative integers can be written as {0, 1, 2, 3, 4, 5, ...}. An integer is any whole number, whether positive or negative. A whole number is a number that can be written without any fractions or decimals. The set of integers from negative five to positive five can be written as {-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5} and contains zero. Sometimes, the term "whole number" is used only to refer to zero and positive whole numbers, while the term "negative whole numbers" is used to refer to whole numbers to the left of zero. The terms "counting numbers" and "natural numbers" also refer to the set of positive integers.