New to mapping software

[jfrazierjr]

From your description, I'm imagining a channel to be a way to allow bright and dark to flow through the layers underneath the channel. If the channel is really dark, the only the darkest parts of the layers beneath it get through. Vice versa for really light. This doesn't have to be an exhaustive definition, just a concept. Am I wrong?

Your a bit off. Remember I said a channel is "one" way to make a mask. The purpose of creating a(or multiple) channel is to be able to apply the same size/shape mask to multiple layers quickly. Think of channels as a layer mask "template" that you can reuse over and over.