Fair Use Doctrine: The fair use doctrine in copyright law allows for the limited use of copyrighted material without the permission of the copyright holder, such as for purposes of commentary, criticism, news reporting, teaching, or research.
Transformative Use: A key factor in the fair use analysis, transformative use refers to the extent to which the new work adds something new, with a further purpose or different character, altering the original with new expression, meaning, or message.
Four-Factor Test: The four-factor test used to determine whether a use is fair, as outlined in the U.S. Copyright Act, includes: the purpose and character of the use, the nature of the copyrighted work, the amount and substantiality of the portion used, and the effect of the use on the potential market for the copyrighted work.