A patent is a grant of a property right to an inventor for an invention. Specifically, a patent grants an inventor "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. A patent grant does not give an inventor the right to make, use, or sell the invention as the patentee may have to adhere to other laws and regulations to make, use, or sell the invention. Because a patent is a property right, it may be sold, licensed, mortgaged, assigned or transferred, given away, or abandoned.

A patent gives the inventor an exclusive right to the invention for a specific period of time, generally 20 years from the date a patent application is filed with the USPTO. U.S. patent grants are effective only within the United States, its territories, and possessions. However, the United States participates in a number of international conventions, which facilitate the application for patents abroad.

The United States Patent and Trademark Office (USPTO) issues three kinds of patents.

  1. Utility patents may be granted to anyone who invents or discovers any new and useful process, machine, article of manufacture, or composition of matter, or any new and useful improvement thereof. These are the most common kinds of patents.
  2. Design patents may be granted to anyone who invents a new, original, and ornamental design for an article of manufacture.
  3. Plant patents may be granted to anyone who invents or discovers and asexually reproduces any distinct and new variety of plant.

To be granted a patent, an invention must be novel and non-obvious. The law provides "that an invention cannot be patented if: "(a) the invention was known or used by others in this country, or patented or described in a printed publication in this or a foreign country, before the invention thereof by the applicant for patent," or "(b) the invention was patented or described in a printed publication in this or a foreign country or in public use or on sale in this country more than one year prior to the application for patent in the United States."

A patent cannot be obtained for just a suggestion or idea. A full description of the actual machine or other subject matter for which a patent is desired is compulsory. The patent specification must be specific enough that a person skilled in the art could make and use the invention, and at the end of the specification, the inventor must include one or more claims that precisely puts the public on notice of what the patent owner can exclude others from making, selling or using. A single patent may include multiple claims, each of which is treated as a distinct invention.

Congress has authority to regulate interstate and foreign commerce under the U.S. Constitution, Article 1, Section 8, Clause 3, sometimes called the Intellectual Property Clause. Congress used this power to enact the Patent Act in 1790, and the first patent was issued under this Act on July 31, 1790, for the making of potash. Patent law may now be found in Title 35 of the United States Code, and federal courts have jurisdiction over patent infringement cases.

The Patent and Trademark Office administers patent law and its patent regulations are found in Parts 2-6 of Title 37 of the Code of Federal Regulations. Patent applications are reviewed by examiners to determine whether they may be granted a patent. Historically, patent applications had to be submitted with a model of the alleged new invention, but now only a detailed specification is necessary in most cases.

If a patent application is rejected, an inventor may request reconsideration in writing, specifically and distinctly enumerating the alleged errors in the patent examiner's action. If on later consideration the rejection is deemed final, the applicant may appeal the decision to the Patents Office's Board of Appeals, with alternative or further review available in the federal courts.

The USPTO does not have jurisdiction over issues of enforcement or infringement of patents. The holder of the patent is responsible for enforcing the patent, and may sue for in the appropriate federal court.