A Summons on a Third-Party Complaint (AO 441) is a court document issued by a judge that orders a third party to appear in court to respond to a complaint. The summons must be served upon the third-party and provides details of the case, including the name of the court, the date and time of the hearing, and the name of the plaintiff. There are two types of Summons on a Third-Party Complaint (AO 441): a Summons with Notice and a Summons and Complaint. The Summons with Notice is the more common type of summons, which requires the third party to appear in court and file a response to the complaint within a specified period of time. The Summons and Complaint requires the third party to appear in court to answer the complaint, as well as any other related claims or counterclaims.