Premise: Metallica is an American heavy metal band based in San Rafael , California . The band 's fast tempos , instrumentals , and aggressive musicianship placed them as one of the founding `` big four '' bands of thrash metal , alongside Megadeth , Anthrax and Slayer . The band expanded its musical direction and achieved substantial commercial success with its eponymous fifth album Metallica ( 1991 ) , which resulted in an album that appealed to a more mainstream audience . Metallica ranks as one of the most commercially successful bands of all time , having sold over 110 million records worldwide .
Hypothesis: Metallica is a band.
Label: ENTAILMENT