Published works created in the United States before March 1, 1989 require a copyright notice to qualify for copyright protection under U.S. law. After the United States joined the Berne Convention for the Protection of Literary and Artistic Works by signing an international treaty, Congress amended the Copyright Act to drop the requirement of a copyright notice on works first published on March 1, 1989 or later.
A standard copyright notice will begin with the copyright symbol -- the letter "c" in a circle -- the word "copyright," or the abbreviation "copr." This is followed by the name of the copyright owner and the year in which the work was first published. A copyright notice can help you track down the copyright owner to request permission to use the work. However, you have to be aware that copyright holder might have sold his copyright to someone else after the copyright notice was affixed to the work.
Even though the use of a copyright notice is no longer a legal requirement for copyright protection in the United States, its use confers significant advantages. A copyright notice can help deter infringement because it indicates that the copyright owner is serious about enforcing his rights. In a copyright infringement lawsuit, the fact that a copyright notice was affixed to the infringed work will prevent the infringing party from claiming "innocent infringement." Innocent infringement means unintentional infringement; it is used by defendants to decrease the amount of damages awarded by the court.
In addition to the Berne Convention, the United States is a member of the Universal Copyright Convention. This allows authors who create a work in the United States to enjoy copyright protection under the laws of any country that is a member of either convention. Most of the countries in the world are members of at least one of these two conventions. Unlike the Berne Convention treaty, however, the Universal Copyright Convention treaty offers international copyright protection only to published works that include a copyright notice. This means that works published in the United States without a copyright notice are not protected in countries that joined the Universal Copyright Convention but not the Berne Convention.