graphics Terms?

[planeswalker99]

I'm curious about the terms that are used with graphics. What do the following mean in relation to each other:
royalty-free
stock
public domain
etc.

Which can be used in commercial use, which can't?

[Vuen]

Uh, I don't think any of those have to do with graphics...

[Vuen]

Unless you're talking about the legal info about the graphics such as copywriting and stuff...

[planeswalker99]

Yah! That is what I was wondering about. Which can be used commercially, which can't?