A quorum is the minimum number of members of a deliberative assembly (a body that uses parliamentary procedure, such as a legislature) necessary to conduct the business of that group. According to Robert's Rules of Order Newly Revised, the "requirement for a quorum is protection against totally unrepresentative action in the name of the body by an unduly small number of persons." In contrast, a plenum is a meeting of the full (or rarely nearly full) body. A body, or a meeting or vote of it, is quorate if a quorum is present (or casts valid votes).