Here's the question you clicked on:
SsgtSyms
Not necessarily a question, but what are your views on what i is when i^2=-1?
i is just that. It is used to denote \[\sqrt{-1}\] and is also used to multiply the magnitude of the imaginary parts on complex numbers
the imaginary part of a complex number is a measure of what stage the phasing is in, then true value of the numbers is oscillating in the complex plane, (going in and out of phase)