Short answers, pulled from the story.
A lawsuit is a proceeding by one or more parties, the plaintiff or claimant, against one or more parties, the defendant, in a civil court of law. The plaintiff claims to have suffered loss from the defendant's actions and asks the court for a legal or equitable remedy.
The plaintiff is the party who brings the lawsuit, claiming loss from the defendant's actions and requesting a remedy. The defendant is the party being sued, who must respond to the complaint or risk a default judgment.
A lawsuit begins when a complaint or petition, known as a pleading, is filed with the court. In a handful of jurisdictions such as the U.S. state of New York, it begins instead when the plaintiff properly serves a summons and complaint on the defendant.
Most lawsuits do not reach trial. An empirical analysis found that less than 2 percent of cases end with a trial, and about 98 percent of civil cases in United States federal courts are resolved without one. Torts settle around 90 percent of the time and overall civil cases settle about 50 percent of the time.
Service of process is the formal delivery of judicial documents to a party in a lawsuit, giving notice of the action and establishing the court's jurisdiction. In federal court, Rule 4(m) of the Federal Rules of Civil Procedure requires service within 90 days of filing the complaint.
A defendant who has no assets in any jurisdiction is called judgment-proof, a colloquial term for an impecunious defendant. Indigent judgment-proof defendants are no longer imprisoned, because debtor's prisons have been outlawed in the vast majority of common law jurisdictions.
The word lawsuit combines law and suit. Suit derives from the Old French suite or sieute, meaning to pursue or follow, which came from the Latin secutus, the past participle of sequi, meaning to attend or follow.