Fair use, in the broadest sense, is the use of copyrighted content without permission from the relevant copyright owner for a restricted and, as the courts define it, “transformative” intent, such as commenting on, criticizing, or parodying such copyrighted work. It is based on the idea that parts of copyrighted works should be free to be used without the copyright owner’s permission. It is a widely used defense by those accused of copyright infringement.
In settling fair use disputes, courts have traditionally looked at four factors:
(1) the intent and character of the use
(2) the nature of the copyrighted work
(3) the volume and substantiality of the portion taken
(4) the impact of the use on the future market.
Section 107 of the Copyright Act provides the statutory framework for determining whether something is fair use and identifies certain types of uses—such as criticism, comment, news reporting, teaching, scholarship, and research—as examples of activities that may qualify as fair use. (Source: Copyright.gov)