The time signature (also known as meter signature, metre signature, bar signature, or measure signature) is a notational convention used in Western musical notation to specify how many beats are in each measure and which note value constitutes one beat. In a musical score, the time signature appears at the beginning of the piece, as a time symbol or 2 stacked numerals. A mid-score time signature, usually immediately following a barline, indicates a change of meter. Meter has an influence upon the rhythms used in a composition, as well as the type of beat. 4/4 is the most common time signature, whereas 3/4 is used in waltzes.