The Copyright Act allows for copyright on the following types of works:
musical works, including any accompanying words;
dramatic works, including any accompanying music;
pantomimes and choreographic works;
pictorial, graphic, and sculptural works;
motion pictures and other audiovisual works;
sound recordings; and
In addition, you can register other works such as computer programs and semiconductor masks.
Registering your copyright ensure that you can bring a timely lawsuit if someone is infringing your work, and early registration increases the amount you can recover in a suit by enabling you to recovery statutory damages.