Plaintiffs are individuals or entities that initiate a legal action by filing a complaint in court, seeking a legal remedy for a grievance. They play a crucial role in the judicial process as the parties who claim to have suffered harm and are seeking compensation or another form of relief from the defendant, who is alleged to have caused the harm. Understanding the role of plaintiffs is vital in navigating the complexities of civil litigation and the rules governing their ability to join others in a lawsuit.