A complex number consists of a real and imaginary number. An imaginary number is any multiple of the square root of -1, i.
A complex number can be expressed in its most basic form as the sum of it's two counterparts, for example 3 + 8i.
This rectangular notation can be converted to polar coordinates as well.
Polar coordinates have a magnitude and angle.
In polar coordinates, the complex number a+bi would have magnitude $ \sqrt(a^2+b^2) $ and angle $ arctan(b/a) $