Metallica released their debut album Kill 'Em All in 1983. The album was issued on July 25, 1983, through the independent label Megaforce Records and introduced the band as a major force in the emerging thrash-metal movement.
Metallica recorded the album in May 1983 at Music America Studios in Rochester, New York, with producer Paul Curcio. The record followed the band's early Los Angeles and San Francisco years, including the addition of bassist Cliff Burton and the replacement of guitarist Dave Mustaine by Kirk Hammett shortly before recording began.
The album was originally planned under the title Metal Up Your Ass, but the name and artwork were changed after concerns from distributors. Kill 'Em All includes “Hit the Lights,” “Seek & Destroy,” “Whiplash,” and “Metal Militia.” It is sometimes confused with Ride the Lightning, Metallica's second album, which was released in 1984. Kill 'Em All's later influence far exceeded its modest initial release, helping define American thrash metal.