A "fretless" instrument is one that does not have the raised metal strips, called frets, on its fingerboard. This design allows musicians to slide their fingers smoothly along the neck, enabling them to produce a continuous range of pitches. Fretless instruments are commonly found in various musical traditions, including jazz, blues, and classical music. Fretless instruments can include stringed instruments like the double bass, cello, and guitar. The absence of frets allows for greater expressiveness and subtle pitch variations, making them popular among players who seek a unique sound. Musicians often use techniques like vibrato and glissando to enhance their performance.