Jazz bass is the use of the double bass or bass guitar, to improvise accompaniment ("comping") basslines and solos in a jazz or jazz fusion style. Players began using the double bass in jazz in the 1890s to supply the low-pitched walking basslines that outlined the harmony of the music. From the 1920s and 1930s Swing and big band era, through Bebop and Hard Bop, to the 1960s-era "free jazz" movement, the resonant, woody sound of the double bass anchored everything from small jazz combos to large jazz big bands.
Beginning in the early 1950s, some jazz bass players began to use the electric bass guitar in place of the double bass. The electric bass, which was easier to amplify, gained particular prominence in the late 1960s and early 1970s jazz subgenre which blended jazz with the amplified electric instruments of rock music, creating jazz fusion.
Most jazz bassists specialize in either the double bass or the electric bass. Some players, such as Stanley Clarke and John Patitucci, have achieved virtuoso skill on both instruments. Whether a jazz bassist is comping (accompanying) or soloing, or playing on a double bass or an electric bass, they usually aim to create a rhythmic drive and "timefeel" that creates a sense of and .
Beginning around 1890, the early New Orleans jazz ensemble (which played a mixture of marches, ragtime, and dixieland music) was initially a marching band with sousaphone (or occasionally bass saxophone) supplying the bass line. As the music moved into bars and brothels, the double bass gradually replaced these wind instruments. Many early bassists doubled on both the "brass bass" and "string bass, " as the instruments were then often referred to. Bassists played "walking" basslines—scale-based lines that outline the harmony.
Because an unamplified double bass is generally the quietest instrument in a jazz band, many players of the 1920s and 1930s used the slap style, slapping and pulling the strings to make a rhythmic "slap" sound against the fingerboard. The slap style cuts through the sound of a band better than simply plucking the strings, and make the bass more easily heard on early sound recordings, as the recording equipment of that time did not capture low frequencies well. For more about the slap style, see "Playing styles, " below.