A patent is the intellectual property right granted by the U.S. Government to an inventor "to exclude others from making, using, offering for sale, or selling the invention throughout the U.S. or importing the invention into the U.S." for a limited time in exchange for public disclosure of the invention when the patent is granted. In most cases, this is twenty years from the date of application. In some situations, the term of the patent may be extended due to delays in the processing of the application. After the patent has expired, the invention becomes public domain. In addition, patent owners must pay a maintenance fee at 3.5, 7.5, and 11.5 years after issue or else the patent will expire.