A patent lawsuit begins with the filing of a complaint alleging patent infringement by the patent holder. If a lawsuit is filed against you, the patent owner must serve two documents on you: (1) a document called a “complaint,” which explains the accusations made against you; and (2) a document called a “summons.” The patent owner may first send a “demand” letter that states that you are potentially infringing the claims of a patent and request that you pay for a license to use the patented invention, or it may go straight to court.