Friction Stir Welding (FSW), invented and patented by TWI in 1991, has given rise to a very large number of related patent filings. Over 1650 filings exist, although not all have succeeded in obtaining a patent. On the surface, it appears that lawyers, attorneys and government patent offices have benefited more from this invention than industry. The filings made cover the application of FSW to particular circumstances, new tooling ideas, products made by FSW, and improvements to the process. This paper reviews the growth in interest in FSW measured by both the real applications in industry and the distribution of related patent filings by time and geography. The key prior art documents and sources are also identified. Some case studies are presented of the most commonly occurring themes. Recommendations are made to help both the new and experienced users of FSW steer their way through the IP forest. TWI's own licensing policy was devised to encourage the rapid adoption of this process and seems to have succeeded with 158 organisations currently holding a FSW licence and the thoughts behind this policy are explained.