The xylophone (from the Greek words meaning, "wood" and "sound,") is a musical instrument where a set of wooden bars (and not fibreglass-reinforced plastic) are placed on a frame and struck with a hammer. The hammer is often made with a wooden head, but many are made of hard plastic. The plastic has to be hard, because soft plastic would absorb some of the vibrations and the sound would be too soft.

Each bar of the xylophone is tuned to a musical note, so that the set of bars makes a musical scale. Some of these instruments have the frame and bars resting over a sound box which makes the sound louder.

The xylophone is a very ancient instrument which probably was first made in Asia. In Africa something similar to a xylophone is called the marimba. Each bar of a marimba has a tubular resonator below it.

Xylophones are recent additions to Western music, and they did not come into use in an orchestra until the late 19th century.