The U.S. Intellectual Property (IP) Ecosystem is one of the most robust and dynamic in the world -- and has been for centuries. The bedrock of this system is the "patent," a legal document that allows its holder exclusive commercialization rights of a part of the "idea space" granted through the patent. Strong legal protection of IP has made the U.S. a destination of great thinkers and innovators worldwide in order to enjoy this legal protection of their valuable insights. A new threat, however, looms. The same legal system that has protected IP has been used to create an organizational form known as a "Patent Troll." Patent Trolls amass patents for the sake of opportunistically extracting rents from firms producing and commercializing products. In this Industry Note, we describe the origin, evolution, costs, benefits, and future outlook for Patent Trolling in the United States.