Copyrighted photos
http://www.kodak.com/global/en/consumer/doingMore/copyright.shtml



stock photos
consists of existing photographs that can be licensed for specific uses
http://www.sxc.hu/


Public domain photos

http://mciu.k12.pa.us/~spjvweb/cfimages.html



Model Release for photos
when you need a signature from someone you took a picture of for some kind of ad

http://www.iballer.com/