Copyright law protects original works of authorship including literary works, music, art, films, and software. The owner of a copyright has the exclusive right to reproduce, distribute, publicly display, and create derivative works of the copyrighted work. However, certain uses of copyrighted materials without permission may be allowed under the fair use doctrine for purposes such as criticism, comment, news reporting, teaching, and research. To determine if a use is fair, courts consider factors such as the purpose and commercial nature of the use, the nature of the copyrighted work, the amount of the work used, and the impact on the market for the work. When in doubt, it is best to obtain permission from the copyright holder.