The term reggae is sometimes used in a broad sense to refer to most types of Jamaican music, including ska, rocksteady and dub. The term is more specifically used to indicate a particular style that originated after the development of rocksteady. In this sense, reggae includes two sub-genres: roots reggae (the original reggae) and dancehall reggae, which originated in the late 1970s. Reggae is founded upon a rhythm style characterized by regular chops on the back beat, known as the skank. This rhythmic style is played by a rhythm guitar and a bass drum hitting on the third beat of each measure, known as the one drop. This beat is slower than that found in reggae'