A fretless bass is a bass with a fingerboard without frets. The fretless fingerboard gives the instrument its characteristic sound, which can be similar to that of a double bass. He is often referred to as "woody", "growling" or "singing". This is caused by the fact that the string being picked does not have contact with the fret, as is the case with a conventional electric bass, but rests directly on the fingerboard. This is why real glissandos are also possible. A much more important criterion, however, is the possibility of differentiated tone formation, which is not available on an instrument with frets. Similar to the double bass, notes can be played with vibrato. The tone can be shaped, the depth of expression of the tones enriched.