When is my work protected?
"Your work is under copyright protection the moment it is created and fixed in a tangible form that it is perceptible either directly or with the aid of a machine or device."
and also,"Copyright, a form of intellectual property law, protects original works of authorship including literary, dramatic, musical, and artistic works, such as poetry, novels, movies, songs, computer software, and architecture. Copyright does not protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed."
(emphasis is mine)
You will find this and all other useful information at U.S. Copyright Office http://www.copyright.gov/help/faq/faq-general.html