The key instrument that provides the core groove of a salsa song is the clave. It is often played with two wooden sticks (called clave) that are hit together. Every instrument in a salsa band is either playing with the clave (generally: congas, timbales, piano, tres guitar, bongos, claves (instrument), strings) or playing independent of the clave rhythm (generally: bass, maracas, güiro, cowbell). Melodic components of the music and dancers can choose to be in clave or out of clave at any point.