A copyright protects an original creative work. Copyrights can be used to protect such works as paintings, books, music, blogs, proprietary systems, and even computer software in some instances.
Technically, once a creative work is "fixed in a tangible medium," it is copyrighted, however, this does not necessarily mean it is protected.
In order to defend yourself against infringers, the work must first be federally registered with the United States Patent and Trademark office.
