Notice Requirements For CopyrightsAlthough the copyrights notice requirement is not essential under United States law, it can be helpful to prove that the infringer had notice of the fact that this work was protected under copyright law; even in the case of old works. This article informs on the copyrights notice requirement.
The following questions have been addressed in this article:Why can notice still hold importance to the copyrighted work?
What are the requirements for demonstrating notice?
What about the notice requirements for unpublished works?