The United States laws provide for three different types of patents:
Utility Patent: A utility patent may be available for inventions which are novel, useful, and non-obvious. Utility patents can be obtained for the utilitarian or functional aspects of an invention. Utility patents have a term of twenty years from the date of filling the patent application with the patent and trademark office, although term extensions are available in certain specific situations. During the term of a utility patent, maintenance fees must be paid in order to sustain the patent. Utility patents are, by far, the most common type of patent issued by the U.S Government.
Design Patent: A design patent can be obtained for the aesthetic appearance of an invention. To be eligible design patent, an invention must be novel, non-obvious and ornamental. In other words, the design must not serve a primarily functional purpose. The outward visible feature of a new light fixture, for example, might be the subject of a design patent. Design patents expire at the conclusion of fourteen from the date of the grant of the patent. Design patents are not subject to maintenance fee payments.
Plant patent: A plant patent may be issued for the invention or discovery of a distinct and new variety of plants, which may be asexually reproduced. To qualify for this type of patent, the discovery or invention must be novel, distinct, and non-obvious. Plant patents have a duration of twenty years from the date of filling of the plant patent application with the patent and trademark office.