A trade secret is a practice, process or formulation that is not known outside the company that gives the company an economic edge or competitive advantage. Trade secrets are often the result of internal research and development. In order to be considered a trade secret, a reasonable effort must be made to conceal the information from the public, the secret must have economic value, and contain information.
This is separate from a patent or copyright in that patents and copyrights are publicly known and available. Copyrighted works are intended for public consumption while patents are publicly available from the U.S. Patent and Trademark Office.