The bass, also called the double bass is the largest and lowest-pitched member of the violin family. Also known as the contrabass, the double bass is usually about 1.8 m (about 6 ft) high and has four strings tuned to sound EE AA D G (EE = third E below middle C; G = second G below middle C) and notated an octave higher. A low fifth string is sometimes added, tuned to the B below the E string. On some instruments, the E string is extended at the head and fitted with a mechanism that clamps off the extra length; releasing the mechanism allows the string to sound the low notes down to D.

Three-stringed basses were common in the 18th and 19th centuries (often tuned A D G) and survive in Eastern European folk music. Early basses of the 16th and 17th centuries had four or five (or, rarely, six) strings. Modern dance-band basses occasionally add a high fifth string tuned to the C above the G string. Until the 19th century, bass players used bows with the stick out-curved in relation to the bow hair—long after the in-curved bow was standard for the violin, viola, and cello. The out-curved bass bow continues in use alongside two in-curved models developed in the 19th century. Virtuosos on the double bass have included the Italian Domenico Dragonetti, the Russian American conductor Serge Koussevitzky, and the American jazz bassist Charlie Mingus.

The bass guitar offers more than supposed by other musicians. As earlier mentioned, the bass is both percussive and melodic. The bass requires a very good sense of time and tone. Unlike the piano and guitar, the bass is not intended to sing over. Although this does happen in modern music, a keyboard, guitar, and/or drums usually accompany it to provide more of an ambiance. In other words, the bass is typically the instrument that connects the beat to the melody.

Bassists, like guitarists, have a variety of techniques to choose from. Chording and soloing are among the possibilities, but other options include slapping and popping. The latter is not intended for guitar but is sometimes employed to create a specific sound.

As stated above, the bass requires a strong sense of time and tone. Because of its very nature, a bass player must be able to “connect” the drums and guitar, much as a keyboard or piano. However, a keyboard or piano does not provide the possibility to slap and pop, or change tune on the fly (commonly done with a hip-shot or D-Tuner – a device that allows a bassist to change tune by a simple flip of a lever). And bassists, like guitarists, can use effects. The most common effects used on bass guitars are chorus, reverb, and compression. However, some bassists use other effects more common to the guitar, like distortion and wah-wah.