"A copyright protects the expression of an idea but it does not protect the idea itself." A copyright protects the way you present the idea in print, on a computer file, on tape, on video, etc. However, anyone can use your ideas as long as they do not directly plagiarize from your work.
The copyright is implicit as soon as your work is expressed in some tangible form. The copyright can be registered with the U.S. Copyright Office for a fee.
A patent is permission granted by a government which gives the applicant a specific period of time before others may legally use, make, or sell an invention without permission. In the patent application, the applicant must fully describe the way the invention was made and how it may be used.
In the United States a patent must be approved by the U.S. Patent and Trademark Office.
Rules regarding copyrights and patents are described more fully in:
Macrina, F. 1995. Scientific integrity. American Society for Microbiology, Washington, D.C.