Most fan labor products are derivative works,[37] in that they are creative additions or modifications to an existing copyrighted work,[38] or they are original creations which are inspired by a specific copyrighted work. Some or all of these works may fall into the legal category of transformative works (such as a parody of the original), which is protected as fair use under U.S. copyright law. However, corporations continue to ask fans to stop engaging with their products in creative ways.