Moot court (sometimes synonymous with mock trial) is an extracurricular activity in many law schools. It is modeled after appellate advocacy. It is not technically the same thing as mock trial, though the two have historically been often confused and as such the terms are often used interchangeably. The term "moot court" refers to mock appellate arguments, while the term "mock trial" refers to a mock trial of fact (usually a jury trial); please see the Mock trial article for details.
In a moot court, participants will typically receive a problem ahead of time. They will research and prepare for that case as if they are lawyers or advocates for one or both of the parties. Participants will then write briefs, participate in oral arguments, or both.
Moot court competitions are typically sponsored by organizations with interest in particular areas of law. The "case" or problem is often one of current interest, sometimes mimicing an actual case, and sometimes fabricated to address difficult legal issues.
Because of the practical experience moot court participants gain, law firms that engage in litigation often look to hire students who have engaged in this activity.