Deep Purple are an English rock band formed in Hertfordshire in 1968. Along with Led Zeppelin and Black Sabbath, they are considered to be among the pioneers of heavy metal and modern hard rock, although the members of the band have always refused to label themselves as heavy metal. The band has also incorporated pop and progressive rock elements. It was once listed by the Guinness Book of World Records as the world's loudest band, and it has sold over 100 million albums worldwide. Deep Purple was ranked #22 on VH1's Greatest Artists of Hard Rock program.