The purpose of fair use is to balance the rights of copyright owners and the benefit to the public.
Fair use is a provision of U.S. Copyright Law that recognizes certain uses of copyright-protected works which do not require permission from the copyright holder. (See Title 17, section 107)
Section 107 describes fair use as follows:
The fair use of a copyrighted work . . . for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include: