"One of several legal limitations on the exclusive rights granted to copyright owners. Fair use permits a second user to copy part or all of a copyrighted work under certain circumstances, even when the copyright holder has not given permission or even objects to that use of the work. Courts evaluate fair use claims case-by-case relying primarily on four factors: the purpose and character of the use of copyrighted work, the nature of the original work, the amount and substantiality of the portion used in relation to the copyrighted work as a whole, and the effect of the use upon the potential market for or value of the original work."
Learn more about Fair Use here: http://www.teachingcopyright.org/handout/fair-use-faq
Adams 12 Fair Use Checklist: http://goo.gl/vE3dKf