The double bass, also called the string bass, upright bass or contrabass, is the largest and lowest-pitched bowedstring instrument in the modern symphony orchestra. The double bass is a member of the string section of the symphony orchestra and smaller string ensembles in classical music. It is also used in other genres such as jazz, 1950s-style blues and rock and roll, traditional country music, bluegrass, tango and folk music.
The double bass can be played either by using a bow or by plucking the strings. The approach to playing the double bass is most often determined by the genres of music. Orchestral, classic and jazz tend to be played with the bow, while in country, blues and rock and roll the bass is often plucked.

Since the 1950s, the bass guitar has largely replaced the double bass in popular music as the bass instrument in therhythm section. While the types of basslines performed by the bassist vary widely from one style of music to another, the bassist fulfills a similar role in most types of music: anchoring the harmonic framework and laying down the beat. The bass guitar is used in many styles of music including rock, metal, pop, punk rock, country, blues, and jazz. It is used as a soloing instrument in jazz, fusion, Latin, funk, and in some rock and metal styles.