Fair use is the right to make some use of copyrighted material without getting permission or paying for its use. It is a basic limit on copyright law that protects free expression. Fair use is a United States legal phrase; however, copyright laws worldwide have limits that keep copyright from being used as a form of private censorship.

Fair use favors uses that:

1. are non-commercial and not sold for a profit;
2. are transformative, adding new meaning and messages to the original;
3. are limited, not copying the entirety of the original; and
4. do not substitute for the original work.

None of these factors is absolutely necessary for fair use, but they all help.