A xylophone is a musical instrument that is part of the percussion family. It belongs to the group which is often called "pitched percussion" or tuned percussion because it can play different pitches and is a different way of expressing the sound that it creats. (notes). Xylophones have bars which are made of wood. People play the xylophone by hitting the bars with a mallet (a kind of drum stick). Each piece of wood is a different length, so they play different notes when they are hit. The bars are arranged like the keys of a piano. Underneath the bars there are long tubes, called resonators, which make the sound last longer.