So...I'm a little confused as to what these pastes are for and what each kind is for.

I'm reading things like red and black and green pastes, diamond pastes, chromium pastes, etc.

What are they all for? Do they sharpen your blade not just strop it? Are they like a cheap solution to sharpening stones or do they just get you by until you can afford a stone?

Just wondering what they're all about. Thanks!