Credit

I just started checking out the Icon communities yesterday. That's how new I am to this, but have quickly become obsessed!

I hope it's okay to ask questions of this sort here. It's not really about making them, but etiquette in regards to sharing. I've looked at the info pages of a few communities, but haven't found my answers.

How does one credit an icon? What is meant by "keyword"? Anything else I should know in regards to using Icons found in these communities?