Fair Use allows the public to use portions of copyrighted work without permission from the copyright owner. To decide whether a use is a fair use, courts look at four factors:
1. The purpose and character of the second use: Is it just a copy, or are you doing something different from the original work? Is your use commercial?
2. The nature of the original: Was the original work creative or primarily factual?
3. Amount used: How much of the original work was used, and was that amount necessary?
4. Effect: Did the use harm the market for the original work? For example, would people buy this work instead of the original?