"Copyright is a form of protection provided by the laws of the United States to authors of “original works of authorship.” When a work is published under the authority of the copyright owner (see definition of “publication” below), a notice of copyright may be placed on all publicly distributed copies or phonorecords. The use of the notice is the responsibility of the copyright owner and does not require permission from, or registration with, the Copyright Office.
Use of the notice may be important because it informs the public that the work is protected by copyright, identifies the copyright owner, and shows the year of first publication. Furthermore, in the event that a work is infringed, if the work carries a proper notice, the court will not give any weight to a defendant’s interposition of an innocent infringement defense—that is, that he or she did not realize that the work was protected. An innocent infringement defense may result in a reduction in damages that the copyright owner would otherwise receive.
For works first published on and after March 1, 1989, use of the copyright notice is optional." U.S. Copyright Office, Public Information Office, Monday through Friday (except legal holidays) between 8:30 a.m. - 5:00 p.m. eastern time. (202) 707-3000. TTY (202) 707-6737.