Plaintiff: This is the person who starts any civil action (law suit) and is making a claim that another person, business, institution, organization, agency, or other type of entity is responsible for causing them damage of some kind and should compensate them for the damage or take other steps to make them whole again.
Defendant: This is the person or other entity that the plaintiff claims is responsible for their damages and is obligated to compensate them or otherwise take steps to make them whole again.
Petitioner: In some types of cases, the issues are not about damage, but are about relationships and resolving matters in those relationships, or creating a way to care for someone who can’t help themselves. In these types of cases, the person asking the court to make decisions is actually “petitioning” the court for a decision or asking the court to give them authority to take certain actions.
Respondent: This is the person who also has an interest in the decision the court may make when the Petitioner files papers asking the court to take action. They are entitled to be notified that papers have been filed with the court asking for a decision or grant of authority, and to “respond” in order to protect any interest that they have in the matter or to ask the court to take different action from what the Petitioner is seeking.
Party: Each person or entity that is named in the papers that start a case is a Party to that action. Every party has a right to be notified of all the procedures that take place in the action, and to respond or participate in each step of the action until its conclusion.