Instruments similar in style to standard guitars, with four strings that generally mimic the attributes of the acoustic double bass. Bass guitars are usually amplified and solid-bodied, although hollow-bodied versions exist (as well as five- and six-stringed versions). The instrument became widely recognized when the Fender company in 1951 produced the “Fender Bass” for the mass market. The electric bass guitar has since become widely used among jazz and rock-and-roll ensembles.