On a typical electric bass, the frets divide the fingerboard by semitones, the same as with a guitar. The first Fender bass guitar had 20 frets, but electric basses today can have 24 frets or even more. There’s a distinct sound to a fretless bass — with a fretted bass, the string is pressed against the fret to determine the note, but with a fretless bass the string is pressed directly onto the fingerboard, as with a standup acoustic bass. The fretless bass requires more attention and skill to play in tune, as your intonation has to be more exact. But there is more freedom to use vibrato, glissando, and to experiment with non-standard tones. Some players will use both fretted and fretless electric basses. Fretless basses are usually associated more with jazz fusion.
The earliest known fretless bass guitar was created by Rolling Stones bassist Bill Wyman in 1961, when he took the frets off a cheap Japanese bass guitar he owned. The first mass-produced fretless electric bass was made my Ampeg in 1966, while Fender waited until 1970 to introduce a fretless version of the Fender Precision bass guitar.
