slide

In performance, a slide is a smooth, continuous movement from one pitch to another — similar to a portamento or glissando. Singers and string players achieve slides naturally by moving the finger or voice smoothly between positions. On a trombone, the slide is the defining mechanism: a U-shaped inner tube that extends and retracts within the outer tubes. The trombone slide has seven standard positions, each lowering the pitch by a semitone. The further out the slide extends, the lower the note. This mechanism gives the trombone a uniquely smooth capability for glissandi and microtonal adjustments. Slide guitar (or bottleneck guitar) uses a glass or metal tube worn on the finger to slide along the strings, creating the characteristic wailing sound of delta blues.