Stats in cPanel

I am looking at the stats of my site and i'm confused. I am using awstats in cPanel.

What are unique visitors? Why is the number of visits higher then the number of unique visits? I have a like 4368 hits? whats a hit?

Maybe these can help:

http://awstats.sourceforge.net/docs/awstats_glossary.html

http://www.mrunix.net/webalizer/webalizer_help.html