A Subpoena (Sub pea-Nah) is a formal document that orders a entity or named individual to appear before a duly authorized body, judge, or court appearance at a specific time to give testimony
This official document is used to order or compel an individual to appear before a court, Grand Jury, Legislative body or other. If a person does not appear they can be charged with contempt of court. Subpoena's can be served by a process server, court official or law enforcement.
Other types of Subpoena's are Subpoena Duces Tecum or instanter. In Some states Subpoena's can be served by phone or by mail.