A patent is a property right granted by the government for a certain period of time. A patent confers “the right to exclude others from making, using, offering for sale, or selling” the invention in the United States or “importing” the invention into the United States. Note that a patent does not give the patent holder the right to make, use, sell, offer to sell, or import the invention; it only provides the right to exclude others from doing so. Sometimes the patent holder must license other patents in order to be able make or use the invention. In the U.S., the term of a patent is 20 years from the date on which the patent application was filed or, in certain cases, from the date an earlier related application was filed. Patents are issued by the U.S. Patent and Trademark Office (USPTO) and by similar government offices in foreign countries, and apply only in the territory in which the patent was granted.