In 1970 the singer Freddie Mercury, the guitarist Brian May, the drummer Roger Taylor and the bassist John Deacon formed the rock band Queen in London. In 1991 its vocalist Freddie Mercury passed away and in 1997 John Deacon retired from the band, however despite these events the band remains active with Brian May and Roger Taylor. Queen is a band that has had great influence on the development of Hard Rock and Heavy Metal. They were among the first bands to make concerts visually appealing shows with the use of innovative elements such as impressive moving light systems, smoke effects, and including audience participation in their shows. Among Queen's early hits are albums like 1974's Sheer Heart Attack and 1975's A Night at the Opera, the latter including the internationally acclaimed single Bohemian Rhapsody. Queen has fifteen studio albums, seven live albums, and tons of compilations. Since Freddie Mercury passed away and the subsequent retirement of John Deacon, May and Taylor have guest-starred on television shows and occasionally performed at special events. Queen is one of the most successful groups of all time with more than 200 million records sold. In a survey carried out by the BBC Radio station in 2007, Queen was ranked as the best group of all time.