The plaintiff’s petition or complaint is the document filed with the court and delivered to the defendant (served) that initiates a lawsuit and puts the defendant on notice of the plaintiff’s claims against the defendant and the relief the plaintiff is asking the court to award (usually money or injunctive relief).

In Maryland, the plaintiff's petition or complaint is the initial legal document filed with a court to start a civil lawsuit. This document outlines the plaintiff's allegations against the defendant, the factual basis for the claims, and the specific relief or damages the plaintiff is seeking. Once the complaint is filed, Maryland law requires that the defendant be properly served with a copy of the complaint and a summons, which informs the defendant of the lawsuit and the requirement to respond within a certain time frame, typically 30 days. The service of process must be conducted in accordance with Maryland Rules, which may include personal delivery, service by mail, or other methods permitted by the court. Failure to properly serve the defendant can result in delays or dismissal of the case. The complaint must also meet certain procedural requirements, such as stating the grounds for the court's jurisdiction, the legal claims being made, and the facts supporting those claims. If the plaintiff is seeking monetary damages, the amount may need to be specified unless claiming an amount for punitive damages or the claim falls under certain exceptions where the amount is not required to be stated.