The most fundamental rhythmic element in salsa music is a pattern and concept known as clave. Clave is a Spanish word meaning 'code,' 'key,' as in key to a mystery or puzzle, or 'keystone,' the wedge-shaped stone in the center of an arch that ties the other stones together. Clave is also the name of the patterns played on claves; two hardwood sticks used in Afro-Cuban music ensembles. The five-stroke clave represents the structural core of many Afro-Cuban rhythms, both popular and folkloric. Just as a keystone holds an arch in place, the clave pattern holds the rhythm together. The clave patterns originated in sub-Saharan African music traditions, where they serve the same function as they do in salsa.