# Imaginary Number Notation

Imaginary numbers, referred to as “complex numbers” on this site, are denoted using the complex constant . The general form of a complex number is shown below, where the real and complex parts of the number are highlighted.

The complex number system extends the normal number system using the properties of the complex constant and the complex coordinate plane. Complex numbers are useful for geometry and trigonometry related problems. See complex number notation for notation examples.