Before digging into the quaternions it is important to have a basic understanding of how the complex numbers are represented. A complex number is expressed in the form of a unique ordered pair (a,b) such that a + bi where a and b are real numbers and i is an imaginary number such that i2 = -1. Show above is a diagram of an arbitrary ordered pair in the complex plane to help visualize this relation, this diagram is also known as an Argand diagram.