An orchestra (; ) is a large instrumental ensemble typical of classical music, which combines instruments from different families, including bowed string instruments such as the violin, viola, cello, and double bass, woodwinds such as the flute, oboe, clarinet and bassoon, brass instruments such as the horn, trumpet, trombone and tuba, and percussion instruments such as the timpani, bass drum, triangle, snare drum, cymbals, and mallet percussion instruments each grouped in sections. Other instruments such as the piano and celesta may sometimes appear in a fifth keyboard section or may stand alone, as may the concert harp and, for performances of some modern compositions, electronic instruments.