Jazz bass is the use of the double bass or bass guitar, to improvise accompaniment ("comping") 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 groups.
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 gained particular prominence in the late 1960s and early 1970s type of jazz known as jazz fusion.
Most jazz bassists specialize in either the double bass or the electric bass. Some players, such as Stanley Clarke and John Patitucci, achieve virtuosity 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 swing and groove.