Ride the Lightning is the second album by the American heavy metal band Metallica, released on July 27, 1984, by the independent record label Megaforce Records. The album was recorded in three weeks with producer Flemming Rasmussen at Sweet Silence Studios in Copenhagen, Denmark. The artwork, based on a concept by the band, depicts an electric chair being struck by lightning flowing from the band logo. The title was taken from a passage in Stephen King's novel The Stand, in which a character uses the phrase to refer to execution by electric chair.

Although rooted in the thrash metal genre, the album showcased the band's musical growth and lyrical sophistication. Bassist Cliff Burton introduced the basics of music theory to the band and had more input in the songwriting. Beyond the fast tempos of its debut Kill 'Em All, Metallica broadened its approach by employing acoustic guitars, extended instrumentals, and more complex harmonies. The overall recording costs were paid by Metallica's European label Music for Nations because Megaforce was unable to cover it. It is the last album to feature songwriting contributions from former lead guitarist Dave Mustaine, and the first to feature contributions from successor Kirk Hammett.

Ride the Lightning received a highly positive response from music critics, who saw it as a more ambitious effort than its predecessor. Metallica promoted the album on the Bang That Head That Doesn't Bang European tour in late 1984, and on its North American leg in the first half of 1985. The band performed at major music festivals such as Monsters of Rock and Day on the Green later that year. Two months after its release, Elektra Records signed Metallica to a multi-year deal and reissued the album. Ride the Lightning peaked at number 100 on the Billboard 200 with virtually no radio exposure and has since reached number 48. Although 75,000 copies were initially pressed for the American market, the album sold half a million by November 1987. It was certified 6× platinum by the Recording Industry Association of America (RIAA) in 2012 for shipping six million copies in the United States. Many rock publications have ranked Ride the Lightning on their best album lists, saying it had a lasting impact on thrash metal.

Metallica released its debut album, Kill 'Em All, on the independent label Megaforce Records on July 25, 1983. The album helped to establish thrash metal, a heavy metal subgenre defined by its brisk riffs and intense percussion. After finishing its promotional tour, Metallica began composing new material, and from September, began performing the songs that were to make up Ride the Lightning at concerts. Because the band had little money, its members often ate one meal a day and stayed at fans' homes while playing at clubs across the United States. An incident occurred when part of Metallica's gear was stolen in Boston, and Anthrax lent Metallica some of its equipment to complete the remaining dates. When not gigging, the band stayed in a rented house in El Cerrito, California, called the Metallica Mansion. Frontman James Hetfield felt uneasy about performing double duty on vocals and rhythm guitar, so the band offered the job to Armored Saint singer John Bush, who turned down the offer because Armored Saint was doing well at the time.^{[citation needed]}

Hetfield gradually built confidence as lead vocalist and kept his original role. Metallica started recording on February 20, 1984, at Sweet Silence Studios in Copenhagen, Denmark. The album was co-produced by Flemming Rasmussen, the founder of Sweet Silence Studios. Drummer Lars Ulrich chose Rasmussen because he liked his work on Rainbow's Difficult to Cure (1981) and was keen to record in Europe. Rasmussen, who had not heard of Metallica, agreed to work on the album, even though his studio employees questioned the band's talent. Rasmussen listened to Metallica's tapes before the members arrived and thought the band had great potential. Metallica rehearsed the album's material at Mercyful Fate's practice room in Copenhagen.

Before entering the studio, Metallica collected ideas on "riff tape" recordings of various jam sessions. Hetfield and Ulrich went through the tapes and selected the strongest riffs to assemble into songs. Together, they record the basic tracks live - only rhythm guitar and drums - with Kirk Hammett and Cliff Burton adding their parts later. Rasmussen, with the support of drum roadie Flemming Larsen, taught the basics of timing and beat duration to Ulrich, who had a tendency to increase speed and had little knowledge of rhythm theory. Drums were recorded in an empty warehouse at the back of the studio, which was not soundproof, and caused reverberation. Although four tracks were already arranged, the band members were not used to creating songs in the studio, as they had not done so for Kill 'Em All. "For Whom the Bell Tolls", "Trapped Under Ice", and "Escape" were written mostly in Copenhagen, and the band put finishing touches on "Fight Fire with Fire", "Ride the Lightning", "Creeping Death", and "The Call of Ktulu", which had already been performed live.

Lead guitarist Kirk Hammett took the album's name from a passage in Stephen King's novel The Stand. The cover art, displaying an electric chair in the midst of lightning bolts, was conceived before recording began. Metallica initially had difficulty recording because gear was stolen three weeks before the band arrived in Copenhagen. The band members slept in the studio by day as they could not afford a hotel and recorded by night, because the studio was booked by other artists during the daytime. Because the group was looking for a major label deal, several A&R representatives from different labels visited the studio. At first, it seemed that Metallica was going to sign with Bronze Records, but the deal was canceled, because Bronze executive Gerry Bron did not appreciate the work done at Sweet Silence Studios, and wanted the US edition to be remixed by engineer Eddie Kramer, and even considered re-recording the album in another studio. Metallica was put off by Bron's failure to share the band's artistic vision and decided to look for another label for the US release, though Bronze had already advertised Metallica as one of its bands.

Metallica had to record quickly because of European shows scheduled 29 days after entering the studio. Recording finished on March 14, and Megaforce released the album on July 27. Although the original album budget was $20,000, the final expense was above US$30,000 (equivalent to $94,711 in 2024). Metallica's European label Music for Nations paid the studio costs because Megaforce owner Jon Zazula could not afford them. Metallica was unhappy with the lack of promotion by Megaforce, and decided to part ways with Zazula. Major label Elektra Records A&R executive Michael Alago noticed Metallica at The Stone gig in San Francisco, and invited Elektra's chairman and the head of promotion to see the August show in New York. The performance at Roseland Ballroom, with Anthrax and Metallica opening for Raven, pleased the Elektra staff, and the band was offered a contract the following morning. On September 12, Metallica signed with Elektra, which re-released the album on November 19. Cliff Burnstein and Peter Mensch of Q Prime were concurrently appointed as the band's new managers. Ride the Lightning is the last Metallica album to feature co-writing contributions from former lead guitarist Dave Mustaine, who received credit on the title track and "The Call of Ktulu". The album also represented the first time Hammett was given writing credits.