Black Sabbath is the debut studio album by the English rock band Black Sabbath. It was released on 13 February 1970 in the United Kingdom by Vertigo Records and on 1 June 1970 in the United States by Warner Bros. Records. The album is widely regarded as the first album in the heavy metal genre. Additionally, the opening track, the self-titled "Black Sabbath", has been referred to as the first doom metal song. According to Black Sabbath's guitarist and founding member Tony Iommi, the group's debut album was recorded in a single day on 16 October 1969. The session lasted twelve hours. Iommi said: "We just went in the studio and did it in a day, we played our live set and that was it. We actually thought a whole day was quite a long time, then off we went the next day to play for £20 in Switzerland." Aside from the bells, thunder and rain sound effects added to the beginning of the opening track and the double-tracked guitar solos on "N.I.B." and "Sleeping Village", there were virtually no overdubs added to the album. Iommi recalls recording live: "We thought, 'We have two days to do it and one of the days is mixing.' So we played live. Ozzy was singing at the same time, we just put him in a separate booth and off we went. We never had a second run of most of the stuff."