Establishing a quorum in a meeting requires the presence of the minimum number of voting members necessary to conduct business legally. Normally, a quorum consists of a majority of voting members, but organizations can determine a different quorum number in their bylaws.
The purpose of a quorum is to ensure that important decisions cannot be made on behalf of an organization by an unreasonably small portion of its membership. An organization can establish the number of voting members required for a quorum as a specific number or a percentage of the total membership.
Robert's Rules of Order states that in the absence of a bylaw, a quorum should be considered to be half of the voting membership. The rules recommends that organizations establish as large a quorum as can be expected to attend most meetings.