Metallica's self-titled 1991 release, known as The Black Album, is the band's fifth studio album.
It followed Kill 'Em All, Ride the Lightning, Master of Puppets, and ...And Justice for All. Those four earlier records established Metallica as a leading thrash metal band before the fifth album broadened its sound.
The record retained heavy guitar work but used shorter, more direct songs and a slower, heavier production style. That shift helped introduce Metallica to a much larger mainstream audience.
Some listeners call it “the fifth Metallica album” while others use “The Black Album.” The latter is an unofficial nickname derived from its nearly black cover and barely visible emblems; the official title is simply Metallica.