1991.. the year of the black album, and the year Metallica made it way out into the spotlight.. they had already conjured up a rather large following during the 80's, but once the black album was released they broke new ground for the genre and became the giants that they are today..  The album has sold over 9000000 copies worldwide, and continues to be on the billboard top 100 list.  There is every reason that this album should be as popular as it is.  Excellent songwriting, excellent production, a full scale in your face metal extravaganza that has been enjoyed by many, even people who aren't fans of the genre.  This album is cause for the saying "Metallica rules. "