Rock music originated from the blending of blues, country, and gospel music in the 1950s. Over 200 subgenres have developed since, including punk, metal, and grunge. Rock revolves around the electric guitar and bass with a strong back beat. It began mainstream with rockabilly and artists like Elvis Presley. Major rock festivals in the 1960s/70s included Woodstock. The genre diversified in the 1980s and saw a decline in popularity in the 1990s with the rise of grunge. Top rock artists according to critics include The Beatles, Rolling Stones, and U2.