The double bass is the lowest voice of the bowed instruments and is the foundation of harmony in the orchestra. It is so large that the player must hold it upright on the floor, and either stand up or sit on a high stool to play. The double bass rests on an adjustable peg and is supported by the body and left knee of the player.

Other names for this instrument when used in folk, bluegrass and jazz are string bass, upright bass and doghouse bass. A person who plays this instrument is called a double-bassist.