Crosby, Stills, Nash & Young are a pioneering folk-rock/rock supergroup that formed from the ranks of three 1960s bands: Buffalo Springfield, The Byrds, and The Hollies. The band is primarily known for their four-part vocal harmonies. They have a strong association with the Woodstock Festival, having played their second ever gig there, and they are one of the few North American groups that rivaled The Beatles in popularity in the late 1960s and early 1970s. They are commonly referred to by their initials CSNY.