Fair use is a doctrine in United States law that permits limited use of copyrighted material without having to first acquire permission from the copyright holder. Fair use is one of the limitations to copyright intended to balance the interests of copyright holders with the public interest in the wider distribution and use of creative works by allowing as a defense to copyright infringement claims certain limited uses that might otherwise be considered infringement. Unlike "fair dealing" rights that exist in most countries with a British legal history, the fair use right is a general exception that applies to all different kinds of uses with all types of works and turns on a flexible proportionality test that examines the purpose of the use, the amount used, and the impact on the market of the original work.

The doctrine of "fair use" originated in common law during the 18th and 19th centuries as a way of preventing copyright law from being too rigidly applied and "stifling the very creativity which [copyright] law is designed to foster." Though originally a common law doctrine, it was enshrined in statutory law when the U.S. Congress passed the Copyright Act of 1976. The U.S. Supreme Court has issued several major decisions clarifying and reaffirming the fair use doctrine since the 1980s, most recently in the 2021 decision Google LLC v. Oracle America, Inc.