Number sets
- Natural numbers (): The counting numbers are commonly called natural numbers; however, other definitions include 0, so that the non-negative integers are also called natural numbers. Natural numbers including 0 are also sometimes called whole numbers.
- Integers (): Positive and negative counting numbers, as well as zero: .
- Rational numbers (): Numbers that can be expressed as a ratio of an integer to a non-zero integer. All integers are rational, but there are rational numbers that are not integers, such as .
- Irrational numbers (): Real numbers that are not rational (cannot be expressed as an integer fraction).
- Real numbers (): Numbers that correspond to points along a line. They can be positive, negative, or zero. Includes all above described sets of numbers.
