Metallica had released four studio albums before Metallica arrived in 1991.
Those earlier records were Kill 'Em All, Ride the Lightning, Master of Puppets, and ...And Justice for All. The 1991 release was therefore the band's fifth studio album, although its self-titled name can make its position in the discography less obvious.
The first four albums established Metallica as a leading thrash metal band. The Black Album preserved the band's heavy foundation but shifted toward slower tempos, clearer production, and more concise songwriting. That change helped the group reach a much broader international audience.
The album's numbering is also easy to confuse with its nickname. Metallica is the official title, while The Black Album is the widely used informal name. Neither title means it was the band's first or only self-titled release.