Patent
A patent is a set of exclusive rights granted by a state to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an invention.
The procedure for granting patents, the requirements placed on the patentee and the extent of the exclusive rights vary widely between countries according to national laws and international agreements. Typically, however, a patent application must include one or more claims defining the invention which must be new, inventive, and useful or industrially applicable. In many countries, certain subject areas are excluded from patents, such as business methods and mental acts. The exclusive right granted to a patentee in most countries is the right to prevent or exclude others from making, using, selling, offering to sell or importing the invention.

# Definition
The term patent usually refers to a right 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. The additional qualification utility patents is used in countries such as the United States to distinguish them from other types of patents but should not be confused with utility models granted by other countries. Examples of particular species of patents for inventions include biological patents, business method patents, chemical patents and software patents.
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 are sometimes called petty patents or innovation patents.  This article relates primarily to the patent for an invention, although so-called petty patents and utility models may also be granted for inventions.
Certain grants made by the monarch in pursuance of the royal prerogative were sometimes called letters patent, which was a government notice to the public of a grant of an exclusive right to ownership and possession.  These were often grants of a patent-like monopoly and predate the modern British origins of the patent system.  For other uses of the term patent see Land patents, which were land grants by early state governments in the USA.  This reflects the original meaning of letters patent that had a broader scope than current usage.

# Law

## Effects
A patent is not a right to practice or use the invention. Rather, a patent provides the right to exclude others 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.  A patent is, in effect, 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.  Like any other property right, it may be sold, licensed, mortgaged, assigned or transferred, given away, or simply abandoned.
The rights conveyed by a patent vary country-by-country. For example, in the United States, a patent covers research, except "purely philosophical" inquiry. A U.S. patent is infringed by any "making" of the invention, even a making that goes toward development of a new invention  which may itself become subject of a patent.  In contrast, Australian law permits others to build on top of a patented invention, by carving out exceptions from infringement for those who conduct research (e.g. for academic purposes) on the invention.
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. If an inventor takes an existing, patented mouse trap design, adds a new feature to make an improved mouse trap, and obtains a patent on the improvement, he or she can only legally build his or her improved mouse trap with permission from the patent holder of the original mouse trap, assuming the original patent is still in force.  On the other hand, the owner of the improved mouse trap can exclude the original patent owner from using the improvement.
Some countries have "working provisions" which require that the invention be exploited in the jurisdiction it covers. Consequences of not working an invention vary from one country to another, ranging from revocation of the patent rights to the awarding of a compulsory license awarded by the courts to a party wishing to exploit a patented invention. The patentee has the opportunity to challenge the revocation or license, but is usually required to provide evidence that the reasonable requirements of the public have been met by the working of invention.

## Enforcement
Patents can generally only be enforced through civil lawsuits (for example, for a US patent, by an action for patent infringement in a United States federal court), although some territories (such as France and Austria) have criminal penalties for wanton infringement. Typically, the patent owner will seek monetary compensation for past infringement, and will seek an injunction prohibiting the defendant from engaging in future acts of infringement.  In order to prove infringement, the patent owner must establish that the accused infringer practices all of the requirements of at least one of the claims of the patent (noting that in many jurisdictions the scope of the patent may not be limited to what is literally stated in the claims, for example due to the "doctrine of equivalents").
An important limitation on the ability of a patent owner to successfully assert the patent in civil litigation is the accused infringer's right to challenge the validity of that patent.  Civil courts hearing patent cases can and often do declare patents invalid.  The grounds on which a patent can be found invalid are set out in the relevant patent legislation and vary between countries.  Often, the grounds are a sub-set of the requirements for patentability in the relevant country.  Whilst an infringer is generally free to rely on any available ground of invalidity (such as a prior publication, for example), some countries have sanctions to prevent the same validity questions being relitigated.  An example is the UK Certificate of contested validity.
The vast majority of patent rights, however, are not determined through litigation, but are resolved privately through patent licensing.  Patent licensing agreements are effectively contracts in which the patent owner (the licensor) agrees not to sue the licensee for infringement of the licensor's patent rights, usually in return for a royalty or other payment.  It is common for companies engaged in complex technical fields to enter into dozens of license agreements associated with the production of a single product.  Moreover, it is equally common for competitors in such fields to license patents to each other under cross-licensing agreements in order to gain access to each other's patents.  A cross license agreement could be highly desirable to the mouse trap developers discussed above, for example, because it would permit both parties to profit off each other's inventions.
The United Nations Statistics Division reports that USA was the top market for patents in force in 2000 closely followed by the EU and Japan.

## Ownership
In most countries, both natural persons and corporate entities may apply for a patent.  The entity or entities then become the owners of the patent when and if it issues. However, it is nearly always required that the inventor or inventors be named and an indication be given on the public record as to how the owner or owners acquired their rights to the invention from the inventor or inventors.
In the United States, however, only the natural person(s) (i.e. the inventor/s) may apply for a patent. If a patent issues, then each person listed as an inventor owns the patent separately from the other.  For example, if two inventors are listed on a patent, then each one may grant licenses to the patent independently of the other, absent an agreement to the contrary.
It is common in the United States for inventors to assign their ownership rights to a corporate entity.  Inventors that work for a corporation, for example, often are required to assign their ownership rights to their corporation as a condition of their employment. Independent inventors often assign their ownership rights to a single entity so that only one entity has the right to grant a license.
The ability to assign ownership rights increases the liquidity of a patent as property.  Inventors can obtain patents and then sell them to third parties.  The third parties then own the patents as if they had originally made the inventions themselves.

## Governing laws
The grant and enforcement of patents are governed by national laws, and also by international treaties, where those treaties have been given effect in national laws.  Patents are, therefore, territorial in nature.
Commonly, a nation forms a patent office with responsibility for operating that nation's patent system, within the relevant patent laws.  The patent office generally has responsibility for the grant of patents, with infringement being the remit of national courts.
There is a trend towards global harmonization of patent laws, with the World Trade Organization (WTO) being particularly active in this area.  The TRIPs Agreement has been largely successful in providing a forum for nations to agree on an aligned set of patent laws.  Conformity with the TRIPs agreement is a requirement of admission to the WTO and so compliance is seen by many nations as important.  This has also led to many developing nations, which may historically have developed different laws to aid their development, enforcing patents laws in line with global practice.
A key international convention relating to patents is the Paris Convention for the Protection of Industrial Property, initially signed in 1883.  The Paris Convention sets out a range of basic rules relating to patents, and although the convention does not have direct legal effect in all national jurisdictions, the principles of the convention are incorporated into all notable current patent systems.  The most significant aspect of the convention is the provision of the right to claim priority: filing an application in any one member state of the Paris Convention preserves the right for one year to file in any other member state, and receive the benefit of the original filing date.  Because the right to a patent is intensely date-driven, this right is fundamental to modern patent usage.
The authority for patent statutes in different countries varies. In the United States, the Constitution empowers Congress to make laws to "promote the Progress of Science and useful Arts..." The laws Congress passed are codified in title 35 of the United States Code and created the United States Patent and Trademark Office. In the UK, substantive patent law is contained in the Patents Act 1977 as amended.
In addition, there are international treaty procedures, such as the procedures under the European Patent Convention (EPC) , and the Patent Cooperation Treaty (PCT) (administered by WIPO and covering 137 countries), that centralise some portion of the filing and examination procedure. Similar arrangements exist among the member states of ARIPO, OAPI, the analogous treaties among African countries.

## Application
A patent is requested by filing a written application at the relevant patent office.  The application contains a description of how to make and use the invention and, under some legislations, if not self evident, the usefulness of the invention.  The patent application may or must also comprise "claims".  Claims define the invention and embodiments for which the applicant wants patent rights.
To obtain a patent, an applicant must provide a written description of the invention in sufficient detail for a person skilled in the art (i.e., the relevant area of technology) to make and use the invention.  This written description is provided in what is known as the patent specification, which is often accompanied by illustrating drawings.  Some countries, such as the United States, further require that the specification disclose the "best mode" of the invention (i.e., the most effective way, to the best of the inventor's knowledge, to make or practice the invention).  In addition, at the end of the specification, the applicant must provide one or more claims that define what the applicant regards as their invention.  A claim, unlike the body of the specification, is a description designed to provide the public with notice of precisely what the patent owner has a right to exclude others from making, using, or selling.  Claims are often analogized to a deed or other instrument that, in the context of real property, sets the metes and bounds of an owner's right to exclude.  The claims define what a patent covers.  A single patent may contain numerous claims, each of which is regarded as a distinct invention.
For a patent to be granted, that is to take legal effect, the patent application must meet the legal requirements related to patentability.
Once a patent application has been filed, most patent offices examine the application for compliance with the requirements of the relevant patent law.  If the application does not comply, the objections are usually communicated to the applicant or their patent agent or attorney, who can respond to the objections to attempt to overcome them and obtain the grant of the patent.
In most countries, there is no requirement that the inventor build a prototype or otherwise reduce his or her invention to actual practice in order to obtain a patent.  The description of the invention, however, must be sufficiently complete so that another person with ordinary skill in the art of the invention can make and use the invention without undue experimentation.
Once granted the patent is subject in most countries to renewal fees, generally due each year, to keep the patent in force.
In Egbert v. Lippmann,104 U. S. 333 (1881) (the "corset case"), the United States Supreme Court affirmed a decision that an inventor who had "slept on his rights for eleven years" without applying for a patent could not obtain one at that time.  This decision has been codified as 35. U.S.C. 102, which bars an inventor from obtaining a patent if the invention has been in public use for more than one year prior to filing.

## Prosecution

# Economics

## Rationale
There are four primary incentives embodied in the patent system: to invent in the first place; to disclose the invention once made; to invest the sums necessary to experiment, produce and market the invention; and to design around and improve upon earlier patents.
- Patents provide incentives for economically efficient research and development (R&D).  Many large modern corporations have annual R&D budgets of hundreds of millions or even billions of dollars. Without patents, R&D spending would be significantly less or eliminated altogether, limiting the possibility of technological advances or breakthroughs. Corporations would be much more conservative about the R&D investments they made, as third parties would be free to exploit any developments. This second justification is closely related to the basic ideas underlying traditional property rights.
- In accordance with the original definition of the term "patent," patents facilitate and encourage disclosure of innovations into the public domain for the common good. If inventors did not have the legal protection of patents, in many cases, they would prefer or tend to keep their inventions secret. Awarding patents generally makes the details of new technology publicly available, for exploitation by anyone after the patent expires, or for further improvement by other inventors. Furthermore, when a patent's term has expired, the public record ensures that the patentee's idea is not lost to humanity.
- In many industries (especially those with high fixed costs and either low marginal costs or low reverse engineering costs  computer processors, software, and pharmaceuticals for example), once an invention exists, the cost of commercialization (testing, tooling up a factory, developing a market, etc.) is far more than the initial conception cost.  (For example, the internal "rule of thumb" at several computer companies in the 1980s was that post-R&D costs were 7-to-1).  Unless there is some way to prevent copies from competing at the marginal cost of production, companies will not make that productization investment.
- Patent rights create an incentive for companies to develop workarounds to patented inventions, thereby creating improved or alternative technologies that might not otherwise be developed.
One interesting side effect of modern patent usage is that the small-time inventor can use the exclusive right status to become a licensor.  This allows the inventor to accumulate capital quickly from licensing the invention and may allow rapid innovation to occur because he or she may choose to not manage a manufacturing buildup for the invention.  Thus the inventor's time and energy can be spent on pure innovation, allowing others to concentrate on manufacturability.

## Criticism
While each of the four incentives is achieved by the patent system in some contexts, the patent system has countervailing costs, and those costs fall more heavily in some contexts than others.  There are many critics and criticisms of patents and this has resulted in the formation of a large number of groups who oppose patents in general, or specific types of patents, and who lobby for their abolishment.
Patents have always been criticized for being granted on already known inventions.  In 1938, for example,  R. Buckminster Fuller, inventor of the geodesic dome wrote:
Patents have also been criticized for conferring a "negative right" upon a patent owner, permitting them to exclude competitors from using or exploiting the invention, even if the competitor subsequently develops the same invention independently. This may be subsequent to the date of invention, or to the priority date, depending upon the relevant patent law (see First to file and first to invent).
Patents may hinder innovation as well. A holding company, pejoratively known as a "patent troll", owns a portfolio of patents, and sues others for infringement of these patents while doing little to develop the technology itself.
Another theoretical problem with patent rights was proposed by law professors Michael Heller and Rebecca Sue Eisenberg in a 1998 Science article. Building from Heller's theory of the tragedy of the anticommons, the professors postulated that intellectual property rights may become so fragmented that, effectively, no one can take advantage of them as to do so would require an agreement between the owners of all of the fragments.
Since at least the early 1980s, patent offices have accepted that computer programs can lie within the realm of patentable subject matter, although the regulations for when a computer program is a patentable invention differ markedly between countries.
In response to perceived problems with the grant of patents, and the evolving nature of technology and industry, there is debate about, and reform of, patent systems around the world.  The TRIPs agreement, developed by the WTO has led to the alignment of many patent systems with regard to certain controversial issues, such as what can be protected by patents and the issue of compulsory licences in cases of national need.

# Etymology
The term "patent" originates from the Latin word patere which means "to lay open" (i.e., make available for public inspection) and the term letters patent, which originally denoted royal decrees granting exclusive rights to certain individuals or businesses.

# History
There is evidence suggesting that something like patents was used among some ancient Greek cities. The creator of a new recipe was granted an exclusive right to make the food for one year, and a similar practice existed in some Roman cities. Patents in the modern sense originated in Italy in 1474. At that time the Republic of Venice issued a decree by which new and inventive devices, once they had been put into practice, had to be communicated to the Republic in order to obtain the right to prevent others from using them.
England followed with the Statute of Monopolies in 1623 under King James I, which declared that patents could only be granted for "projects of new invention."  During the reign of Queen Anne (17021714), the lawyers of the English Court developed the requirement that a written description of the invention must be submitted.  These developments, which were in place during the Colonial period, formed the basis for modern English and United States patent law.
In the United States, during the colonial period and Articles of Confederation years (17781789), several states adopted patent systems of their own.  The first Congress adopted a Patent Act, in 1790, and the first patent was issued under this Act on July 31, 1790 (and the subject matter of that patent was for the making of potash).