A party is a person or group of persons that compose a single entity which can be identified as one for the purposes of the law. Parties include: plaintiff (person filing suit), defendant (person sued or charged with a crime), petitioner (files a petition asking for a court ruling), respondent (usually in opposition to a petition or an appeal), cross-complainant (a defendant who sues someone else in the same lawsuit), or cross-defendant (a person sued by a cross-complainant).