Crosby, Stills & Nash (CSN) was a folk rock supergroup composed of the American singer-songwriters David Crosby (formerly of the Byrds) and Stephen Stills (formerly of Buffalo Springfield) and the English-American singer-songwriter Graham Nash (formerly of the Hollies). When joined by the Canadian singer-songwriter Neil Young (also formerly of Buffalo Springfield), they were known as Crosby, Stills, Nash & Young (CSNY). They are noted for their intricate vocal harmonies and lasting influence on American music and culture, their political activism... [more on Wikipedia]