As the name suggests, a fretless guitar is a guitar without any frets acting as the lower end node of a vibrating string. Although they are played essentially the same way as other guitars, fretless guitars offer trained musicians more creative possibilities than fretted guitars because they can support a variety of different playing styles and are not bound to the standard chromatic scale.
Fretless acoustic guitars have dampened vibrations that create a softer, muted sound. In addition, many R&B, jazz and funk musicians prefer using fretless electric bass guitars because they have a similar sound and feel to the acoustic double bass. The fretless guitar also allows for more direct contact with the notes played because the finger tip, rather than the fret, determines the string length and, consequently, the pitch of the note.
Combining Guitar Styles
Fretless guitar playing is closely related to slide guitar playing. The lack of frets on the guitar allows musicians to create a slide guitar-like sound using only their finger tips. Fretless guitar players can combine slide guitar and fingered guitar playing techniques to produce a larger range of tonal and harmonic capabilities than one would get from a typical fretted guitar.
Unlike fretted guitars, fretless guitars are not constrained by specific musical tunings or tuning systems. This is especially beneficial when playing non-Western music that incorporates notes outside of 12-tone scales.
On a fretless guitar it is possible to play every pitch in between the standard notes used in Western music, allowing players to utilize microtonal musical intervals and even compensate for bad tuning mid-song. For instance, if a fretless bass guitar player realizes that his F string is flat, he can play the rest of the F string notes slightly sharper than usual to make them sound in tune even though the string is out of tune.