Bass (pronounced "base") describes musical instruments that produce tones in the low-pitched range. They belong to different families of instruments and can cover a wide range of musical roles. Since producing low pitches usually requires a long air column or string, the string and wind bass instruments are usually the largest instruments in their families or instrument classes.
The bouble bass from the viol or violin family is usually the instrument referred to as a "bass" in European classical music and jazz. Sometimes called a "string bass" to differentiate it from a "brass bass" or "bass horn" or "upright bass" to differentiate it from a "bass guitar".
The double bass, also called the string bass, upright bass, standup bass or contrabass, is the largest and lowest-pitched bowed string instrument in the modern symphony orchestra, with strings usually tuned to E1, A1, D2 and G2 (see standard tuning). The double bass is a standard member of the string section of the symphony orchestra and smaller string ensembles in Western classical music. In addition, it is used in other genres such as jazz, 1950s-style blues and rock and roll, rockabilly/psychobilly, traditional country music, bluegrass, tango and many types of folk music. A person who plays the double bass is usually referred to as a bassist.