"Fair use" is an exception to United States copyright law that allows for the reproduction of limited portions of a copyrighted works for limited purposes such as criticism, commentary, parody, news reporting, research and teaching. 

Fair use does not grant rights to redistribute copyrighted works in their entirety for non-commercial or educational purposes, nor does it grant rights to redistribute copyrighted works that you have previously purchased.

Fair use is a complicated and highly subjective doctrine. You may be liable for monetary damages if you use copyrighted work in a manner that is determined by a court of law to not meet the standard of fair use.