Crosby, Stills & Nash (CSN) was a folk rock supergroup made up of American singer-songwriters David Crosby and Stephen Stills, and English singer-songwriter Graham Nash. When joined by Canadian singer-songwriter Neil Young as a fourth member, they are called Crosby, Stills, Nash & Young (CSNY). They are noted for their lasting influence on American music and culture, and for their intricate vocal harmonies, often tumultuous interpersonal relationships, and political activism.
CSN formed in 1968 shortly after Crosby, Stills and Nash performed together informally in July of that year, discovering they harmonized well. Crosby had been asked to leave The Byrds in late 1967, and Stills' band Buffalo Springfield had broken up in early 1968; Nash left his band The Hollies in December, and by early 1969 the trio had signed a recordi…Read more on Wikipedia