**What is an integer?**

An integer is a whole number that can be positive, negative, or zero. An Integer is naturally defined as a number that can be written without a fractional component.

Example,

Integers are: 45, 89, 6, 0, and -543, -87.

Numbers that are not integers are: 6.50, 9 1/2, and -8.152 .

The set of integers consists of zero (0), the positive natural numbers (1, 2, 3, …), also called whole numbers or counting numbers, and their additive inverses (the **negative integers**, i.e., −1, −2, −3, …).

The set of integers is often denoted by a boldface letter ‘Z’ (“**Z**“) or blackboard bold ℤ.

ℤ is a subset of the set of all rational numbers ℚ, which in turn is a subset of the real numbers ℝ. Like the natural numbers, ℤ is countably infinite.