In legal terminology, a complaint is any formal legal document that establishes the facts and legal reasons for a lawsuit. A complaint must list the reasons for the plaintiff's case, and it must ask for a specific legal remedy. Once a complaint is filed with the court a summons (an order from the court) is notifies the defendant a lawsuit has been filed against them. Once a defendant receives notice of a complaint, they must reply within a specified period of time with an answer. Complaints are pleadings that must be written carefully to properly state the facts and legal basis for the claim. Usually this requires the help of an attorney.