What is "altar bell"

n. (''in the Roman Catholic Church'') a bell rung at significant times during the Mass

In the Latin Rite of the Catholic Church, in Lutheranism, in Methodism, and in the Anglican Communion, an altar or sanctus bell is typically a small hand-held bell or set of bells. The primary reason for the use of sanctus/altar bell(s) is to create a joyful noise to the Lord as a way to give thanks for the miracle taking place atop the Altar of Sacrifice. An ancillary function of the bell(s) is to focus the attention of those attending the Mass that a supernatural event is taking place on the altar. Such bells are also commonly referred to as the Mass bell, sacring bell, Sacryn bell, saints' bell, sance-bell, or sanctus bell (or "bells", when there are three). and are kept on the credence table or some other convenient location within the sanctuary.