Patents are a form of personal property.
The patent owner has the right to exclude others from making, selling, offering for sale, or importing into the U.S. the invention protected by the patent, unless they have the express permission of the patent holder to do so. The patentee can grant these rights to others through licensing contracts or by outright sale of the patent. For example, the inventor of an automobile carburetor might not be allowed to use it, if someone else had a patent on the car itself. The rights to patent protection are set forth by the United States Constitution in Article I, Section 8. The Patent Laws are elaborated in the United State Code, title 35.