Tap dance is a form of dance characterized by using the sound of one's tap shoes hitting the floor as a percussive instrument. As such, it is also commonly considered to be a form of music. Two major variations on tap dance exist: rhythm (Jazz) tap and Broadway tap. Broadway tap focuses more on the dance. It is widely performed as a part of musical theater. Rhythm tap focuses more on musicality, and practitioners consider themselves to be a part of the Jazz tradition. The sound is made by shoes with a metal "tap" on the heel and toe. Tap shoes can be bought at most dance shops. There are different brands of shoes which sometimes differ in the way they sound. "Soft-Shoe" is a rhythm form of tap dancing that doesn't require special shoes, and while rhythm is generated by tapping of the feet, it also uses sliding of the feet (even sometimes using scattered sand on the stage to enhance the sound of the performer's sliding feet) more often than modern rhythm tap. It preceded what is currently considered to be modern tap, but has since declined in popularity.