A writ of mandamus is a legal tool used to compel a government official or agency to perform a specific duty. Sometimes, this writ is also called a "mandate," "order," or "writ of mandate." These terms all refer to the same legal process, and all have the same important underlying meaning: that the court is ordering a government actor to do something that they are required to do but have not done yet. Other similar legal processes include a writ of habeas corpus, which is used to challenge a person's detention or imprisonment, and a writ of certiorari, which is used to request that a higher court review a lower court's decision.