Metallica was first formed by Lars Ulrich, James Hetfield, and future Megadeth member Dave Mustaine and Ron McGovney. They first played in L.A., but later found themselves at home playing in the San Francisco Bay area. The band later replaced Ron with Cliff Burton and Dave with Kirk Hammet as late as 1983.

On September 27, 1986, on the European leg of the Master of Puppets tour, Cliff Burton was killed in a bus accident in Sweden en route to their next show's location. Tragic as this event was, Metallica continued on and Cliff was replaced by Jason Newsted, who remained part of the band until 2001, when he finally annouced he would leave Metallica because of the damage he had done to his body touring and headbanging for fourteen years.

More than any other band, Metallica and their albums have been the yardstick with which to measure other heavy metal releases. Metallica practically defines "heavy metal" as a sub-genre of metal itself, although their music ranges from NWOBHM to Thrash in their earlier days. However, in the 1990s and beyond 2000, Metallica evolved a more mainstream sound, which helped them become a household name and the seventh biggest selling act in history.