A patent is the formal document issued by PTO following the successful prosecution of a patent application. Typically, a patent application remains pending with the PTO for several years. The time period between filing of a patent application and the issuance of a patent is referred to as "prosecution."
Patents are a useful source of prior art information. A patent concludes with a series of numbered sentences. The numbered sentences, referred to as claims, specify what the inventor(s) regards as the invention.