I thought I'd clear up some questions about copyright. I posted this ontop of another topic but I'm reposting this part on it's own for better reading.
This is from http://www.copyright.gov/help/faq/faq-fairuse.html
How much of someone else's work can I use without getting permission?
Under the fair use doctrine of the U.S. copyright statute, it is permissible to use limited portions of a work including quotes, for purposes such as commentary, criticism, news reporting, and scholarly reports. There are no legal rules permitting the use of a specific number of words, a certain number of musical notes, or percentage of a work. Whether a particular use qualifies as fair use depends on all the circumstances. See also FL 102, Fair Use, and Circular 21, Reproductions of Copyrighted Works by Educators and Librarians.
Now of course if I were to post something that belonged to some one else claiming it was my work and not attributing copyright then I would be in violation of copy right.