To be patentable, an invention must meet four primary requirements. First, the invention must fall within at least one category of patentable subject matter. According to the Patent Act of 1952, an invention which is a “process, machine, manufacture, or composition of matter” is eligible for patent protection. Second, the invention must be useful, a requirement that is satisfied if the invention is operable and provides a tangible benefit. Third, the invention must be novel, or different, from subject matter disclosed by an earlier patent, publication, or other prior art. Finally, an invention is patentable if it would not be obvious to a person of ordinary skill in the art.