A fretless bass is an electric bass guitar whose neck lacks frets and thus is smooth like traditional string instruments, and like the neck of an acoustic double bass. While the fretless bass is played in all styles of music, it is most common in pop, rock, and jazz. It first saw widespread use during the 1970s, although some players used them before then.
The Fender Precision Bass was introduced in 1951, with frets to help performers find the proper note (i.e. to provide precision). This concept of the fretted bass guitar has since become the standard, as other companies followed with similar electric fretted basses, like the Höfner 500/1 of Beatle Paul McCartney, which resembled a viol but with frets.