Metallica grew from the fledgling thrash metal scene of the early 1980s to become one of the biggest metal acts in the history of music. They still play sell out concerts around the globe and their music is critically acclaimed. Their story is one of excess, success and very heavy metal. Their music has been constantly innovative, breaking the boundaries of what constitutes heavy metal and skilfully appealing to a huge global audience. As early as 1986, Master of Puppets was seen as the album that broke thrash to the wider audience, and by the time Metallica (the black album) came out in 1991, it cemented their reputation as metallers who remained faithful to the core, but were able to adapt and make themselves hugely popular.