What does Audssey actually do?

[02Lightning]

I’ve been reading a lot on it lately and I think what it does is balance your speakers using a mic as a SPL meter? Could this same thing be achieved with a SPL meter and some pink or white noise and adjust the dB level of each speaker from a certain spot? Is this pretty much the gist of it? I’m also not sure how frequencies come in to play, because from reading, I should set all my speakers to 80Hz for the low limit and 80Hz for the sub on the high limit.