Fair use is part of United States copyright law that permits the use of copyrighted material in certain circumstances, aiming to balance the exclusive rights of copyright owners with the public interest in the dissemination of information. It applies to various uses including criticism, comment, news reporting, teaching, scholarship, and research. The determination of fair use is fact-specific, assessed based on four factors: the purpose and character of the use (commercial or educational), the nature of the copyrighted work, the amount and substantiality of the portion used in relation to the whole work, and the effect of the use upon the market value of the original work.