An Argand diagram is a method of visualising complex numbers by plotting them on a 2D plane, similar to a Cartesian diagram. However, instead of and axes, we instead have real and imaginary axes respectively.
It’s like if we took a number line:
And extended it into a new dimension with the Imaginary Number DLC:
Note how the axes are labelled with and , to represent the real and imaginary axes respectively.
This now gives us a way to plot arbitrary complex numbers as points or vectors in 2D space!
Some example points are shown below: