Copyright exists to protect the rights of authors and other creators, by ensuring that they are able to make money from their work. In order to also protect the exchange of ideas necessary for innovation and other public interests, copyright expires after a period of time, and is subject to some limitations, such as Fair Use. Libraries and educational purposes have special rights under U.S. copyright law. The links below give more information on copyright law, and the rules for using copyrighted materials legally in your courses.