According to the U.S. Copyright Office, "Copyright is a form of protection grounded in the U.S. Constitution and granted by law for original works of authorship fixed in a tangible medium of expression. Copyright covers both published and unpublished works."
"Copyright, a form of intellectual property law, protects original works of authorship including literary, dramatic, musical, and artistic works, such as poetry, novels, movies, songs, computer softwar, and architecture. Copyright does NOT protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed."