<Table> <Tr> <Td> </Td> <Td> This article relies too much on references to primary sources . Please improve this by adding secondary or tertiary sources . (April 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article relies too much on references to primary sources . Please improve this by adding secondary or tertiary sources . (April 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> The copyright law of the United States tries to encourage the creation of art and culture by rewarding authors and artists with a set of exclusive rights . Copyright law grants authors and artists the exclusive right to make and sell copies of their works, the right to create derivative works, and the right to perform or display their works publicly . These exclusive rights are subject to a time limit, and generally expire 70 years after the author's death . In the United States, any music composed before January 1, 1923, is generally considered public domain . </P> <P> United States copyright law is governed by the Copyright Act of 1976 . The United States Constitution explicitly grants Congress the power to create copyright law under Article 1, Section 8, Clause 8, known as the Copyright Clause . Under the Copyright Clause, Congress has the power, "To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries ." </P>

What type of protection does u.s. law grant the creator of a book film or piece of music