Real numbers

In mathematics, the field of real numbers is the standard construction of a mathematical object which formalises the intuitively expected behaviour of what is usually referred to simply as numbers with regard to arithmetic operations and ordering. It is distinguished from the field of rational numbers by having the additional property of order completeness, Cauchy completeness, or the nested interval property, which are all equivalent in this context.

Every integer or rational number is a real number, but "infinity" or infinitesimal numbers are not.