The double bass, also known simply as the bass, amongst other names, is the largest and, therefore, lowest-pitched chordophone in the modern symphony orchestra (excluding unorthodox additions such as the octobass). Similar in structure to the cello, it has four, although occasionally five, strings.
The double bass is played with a bow (arco), or by plucking the
strings (pizzicato), or via a variety of extended techniques.
In orchestral repertoire and tango music, both arco and
pizzicato are employed. In jazz, blues, and rockabilly,
pizzicato is the norm. Classical music and jazz use the natural
sound produced acoustically by the instrument, as does traditional
bluegrass. In funk, blues, reggae, and related genres, the double bass
is often amplified.