In order to qualify for a patent, a development must overcome two basic hurdles when compared to pre-existing technology. First, an invention must be new, and must have never existed before as a single cohesive item. Second, the invention must not be an obvious development when considered against the entire background of pre-existing technology. These two tests, novelty and of nonobviousness, are the principal criteria applied by the Patent Ofﬁce along with the formal requirements regarding adequate disclosure of information relating to the invention.
The United States Patent and Trademark Ofﬁce is interested in promoting the good of the United States public, and therefore a patent application is compared to prior technology that is at least theoretically available to the United States public at large. For this reason, prior technology, referred to as "prior art," is evaluated from a variety of sources. Patents and printed publications generated anywhere in the world are considered since they could at least theoretically be found by members of the United States public by searching libraries and the like. Other forms of prior art, although typically less available during examination of a patent application, includes public disclosures occurring anywhere in the world.