The number pi, which has a constant value that approximately equals 3.14, is an irrational number. It is a type or real number that cannot be expressed as a common fraction. It has an infinite or endless decimal representation, without any repeating pattern.
Pi, by definition, is the ratio of a circle's circumference to its diameter. The result when the circumference of a circle is divided by its diameter, is a constant with a decimal extension that neither terminates nor becomes periodic. Its closest decimal equivalent is 22/7.
Pi is also a transcendental number, which simply means it is not an algebraic number, nor a root of any nonzero polynomial comprising of rational coefficients. All transcendental numbers are also irrational.