What is a subpoena?

A subpoena is specifically defined as a court order that requires an individual to appear and testify at a legal proceeding, such as a trial or deposition. It is an essential tool in the judicial system, ensuring that witnesses provide their testimony or evidence when required by law. This legal instrument is used to compel a person's presence in court, thus emphasizing the authority of the court to summon individuals to fulfill their legal obligations.

While other options may seem related to legal processes, they do not accurately capture the essence of what a subpoena is. A formal request for a document does not encompass the requirement of personal appearance, and the same applies to the term used for private meetings, which does not involve a court directive. Meanwhile, a notification of a court date may inform someone about when they need to appear, but it does not serve the same function and binding nature as a subpoena. Hence, the defining characteristic of a subpoena is its role as a court order compelling someone to appear, making the selection of that answer clearly correct.