Patent

A patent is a limited property right that the government offers to inventors in exchange for their agreement to share the details of their inventions with the public. A patent is not a right to practice or use the invention. Rather, a patent provides the right to exclude other from making, using, selling, offering for sale, or importing the patented invention for the term of the patent, which is usually 20 years from the filing date subject to the payment of maintenance fees.

A patent being an exclusionary right does not, however, necessarily give the owner of the patent the right to exploit the patent. For example, many inventions are improvements of prior inventions which may still be covered by someone else's patent.

Like any other property right, it may be sold, licensed, mortgaged, assigned or transferred, given away, or simply abandoned.

The invention claimed in a patent may be any new and useful process, machine, article of manufacture, or composition of matter or any new and useful improvement. The invention has to be new, inventive, and useful or industrially applicable.

Some other types of intellectual property rights are referred to as patents in some jurisdictions: industrial design rights are called design patents in some jurisdictions (they protect the visual design of objects that are not purely utilitarian), plant breeders' rights are sometimes called plant patents, and utility models or “Gebrauchsmuster”.

(source: http://en.wikipedia.org/wiki/Patent)