# imaginary number

An imaginary number is a number whose square is negative. Every imaginary number can be written
in the form *ib* where *b* is a real
number and *i* is the imaginary unit, √-1, with the property that *i*^{ 2} = -1. For example, √-16
is an imaginary number, since √-16 = √-1.√16 can be written
as 4*i*.

Imaginary numbers are complex numbers in which the real part is zero. In the representation of complex numbers on the complex plane (Argand diagram), imaginary numbers lie on the *y*-axis. The term "imaginary" is unfortunate because
it suggests something that has less reality than a "real" number, which
isn't the case.