Abbreviation for Soprano, Alto, Tenor, Bass. Usually found on choir music, indicating which voices the piece is arranged for. SATB is the widest selection of voices, with two parts for both women and men, and often music written for SATB will have the soprano section split in two in places for additional effect. (cf: SSA, SAB) Commonly a piece will have multiple arrangements appropriate for different groups - sometimes in different keys and with the melody in different voices to accommodate the different vocal ranges of the four voices, so choosing the correct one is very important.