The use of a copyright notice is no longer required under the U.S. law, although it is often beneficial. Prior law did contain such a requirement, so the use of notice is still relevant to the copyright status of older works.
Notice was required under the 1976 Copyright Act. This requirement was eliminated when the United States adhered to the Berne Convention in 1989. Works published without notice before that date could have entered the public domain. See the Public Domain section of this guide for further information.
Use of the notice may be helpful because it informs the public that the work is protected, identifies the copyright owner, and provides the year of first publication. Furthermore, a proper copyright notice provides protection in the case of infringement.
The use of the copyright notice is the responsibility of the copyright owner and does not require advance permission from, or registration with, the Copyright Office. See the U.S. Copyright Office's Circular 3 Copyright Notice publication for further details.