Alberti bass

Alberti bass is a kind of broken chord[?] or arpeggiated accompaniment, where the notes of the chord are presented in the order lowest, highest, middle, highest. This pattern is then repeated. A well known example is found at the beginning of Wolfgang Amadeus Mozart's Piano Sonata, K 545:

Alberti bass is usually found in the left hand of pieces for keyboard instruments. However, it is sometimes found in instrumental pieces, Bela Bartok using it towards the end of his String Quartet No. 5, for example.