Definition

• According to the U.S. Patent and Trademark Office (USPTO), a patent is a grant of a property right to an inventor for a fixed amount of time, usually twenty years. The patent statute's language states that the property right granted is "the right to exclude others from making, using, offering for sale, or selling" or "importing" patented materials. A U.S. patent is only valid in the United States, although inventors may file patent applications in other countries.
  
  

What Can Be Patented

• According to the USPTO, patentable materials generally fall into one of three categories:
  
  1.) Utility patents, which cover inventions that are useful in some way;
  2.) Design patents, which cover the unique design elements of an item;
  3.) Plant patents, which cover newly created genes in asexually reproduced plants.
  
  The majority of patents granted in the U.S. are utility patents. Although "utility" under patent law has been extended to cover non-tangible objects such as business methods and improvements in operating procedures, it does require that the item or process be useful in some way. For instance, a machine that does not work cannot be patented, for an inoperable machine is not "useful" in the sense required by the statute.
  
  

Novelty

• The elements of an invention that a patent protects are its "novel" elements, according to PatentApplications.net. Whether an element of an invention is novel or unique is measured against what is already known and used in the industry, also known as the "prior art." If an invention contains both elements covered by prior art and elements that are novel, the patent will protect only the novel elements.
  
  

Detecting Infringement

• According to the USPTO, its responsibility in the patent process is only to review patent applications and issue patents. Enforcing a patent is the job of the patent holder. The first step in determining whether a patent is being infringed upon is to compare the elements in the patent, or the "claims," with the potentially infringing product. If a potentially infringing product is described exactly by the "claims" in the issued patent, it is said to "read on" or "teach" the patent's claims, and is likely infringing.
  
  

Enforcement

• According to FindLaw, if a patent holder believes another product infringes his or her patent, the patent holder may file a lawsuit in U.S. federal court against the infringer. Usually, courts that find an infringement has occurred will choose one of two options: either the court will issue an injunction prohibiting the infringer from using the infringing material, or the court will arrange for the infringer to pay royalties to the patent holder.
  
  One danger in bringing a patent infringement suit is that the alleged infringer may defend his or her case by arguing that the patent is invalid -- in other words, that the USPTO made a mistake in issuing the patent in the first place. If the court agrees, it may revoke the patent. The danger of patent revocation often leads patent holders to try to work out royalty agreements with suspected infringers outside of court, rather than bringing a lawsuit.