A fretless bass is a type of bass guitar that does not have frets, which are the metal strips found on the neck of traditional bass guitars. This design allows for a smoother, continuous surface, enabling players to slide between notes and create a unique sound. Fretless basses are often used in genres like jazz, fusion, and world music, where expressive playing is essential. Players of the fretless bass must develop a keen sense of pitch, as there are no frets to guide finger placement. Notable musicians, such as Jaco Pastorius, have popularized the instrument, showcasing its versatility and expressive capabilities in various musical contexts.