Metallica is an American heavy metal band from Los Angeles, California, formed in 1981. The band was founded when James Hetfield responded to an advertisement that drummer Lars Ulrich had posted in a local newspaper. Metallica's line-up has primarily consisted of Ulrich, rhythm guitarist and vocalist James Hetfield and lead guitarist Kirk Hammett, while going through a number of bassists (Ron McGovney, Cliff Burton, Jason Newsted). The spot is currently held by Robert Trujillo. The band's original lead guitarist, before Hammett, was current Megadeth guitarist and lead vocalist Dave Mustaine.

Metallica's early releases included fast tempos, instrumentals, and aggressive musicianship that placed them as one of the "big four" of the thrash metal subgenre alongside Slayer, Megadeth, and Anthrax during the genre's development into a popular style. The band earned a growing fan base in the underground music community and critical acclaim, with the 1986 release Master of Puppets described as one of the most influential and "heavy" thrash metal albums. The band achieved substantial commercial success with their eponymous fifth album (also known as The Black Album), which debuted at number one on the Billboard 200. With this release the band expanded its musical direction resulting in an album that appealed to a more mainstream audience.

In 2000, Metallica was among several artists who filed a lawsuit against Napster for sharing the band's copyright-protected material for free without any band member's consent. A settlement was reached, and Napster became a pay-to-use service. Despite reaching number one on the Billboard 200, the release of St. Anger alienated many fans with the exclusion of guitar solos and the "steel-sounding" snare drum. A film titled Some Kind of Monster documented the recording process of St. Anger and the turmoil within the band during that time.

Metallica has released nine studio albums, three live albums, two EPs, 24 music videos, and 45 singles. The band has won nine Grammy Awards, and has had five consecutive albums debut at number one on the Billboard 200, making Metallica the first band to do so; this record was later matched by the Dave Matthews Band. The band's 1991 album, Metallica, has sold over 15 million copies in the United States, and 22 million copies worldwide, which makes it the 25th-highest-selling album in the country. In December 2009, it became the highest-selling album of the SoundScan era, surpassing 1997's Come On Over by country artist Shania Twain. The band has sold an estimated 100 million records worldwide as of the release of their latest album, Death Magnetic. As of December 2009, Metallica is the fourth best-selling music artist since the SoundScan era began tracking sales on May 25, 1991, selling a total of 52,271,000 albums in the United States alone.

Metallica was formed in Los Angeles, California, in late 1981 when drummer Lars Ulrich placed an advertisement in a Los Angeles newspaper—The Recycler—which read "Drummer looking for other metal musicians to jam with Tygers of Pan Tang, Diamond Head and Iron Maiden." Guitarists James Hetfield and Hugh Tanner of Leather Charm answered the advertisement. Although he had not formed a band, Ulrich asked Metal Blade Records founder Brian Slagel if he could record a song for the label's upcoming compilation Metal Massacre. Slagel accepted, and Ulrich recruited Hetfield to sing and play rhythm guitar. The band was officially formed in October 1981, five months after Ulrich and Hetfield first met.

In May 1983, Metallica traveled to Rochester, New York to record its first album, Metal up Your Ass, with production duties handled by Paul Curcio. Band members decided to kick Mustaine out of the band due to drug and alcohol abuse and violent behavior just prior to the sessions on April 11, 1983. Exodus guitarist Kirk Hammett flew in to replace Mustaine the same afternoon.

Mustaine, who went on to found Megadeth, has expressed his dislike for Hammett in interviews. He said Hammett "stole my job." Mustaine was "pissed off" because he believes Hammett became popular by playing the guitar leads that Mustaine wrote. In a 1985 interview with Metal Forces, Mustaine slammed Hammett saying, "it's real funny how Kirk Hammett ripped off every lead break I'd played on that No Life 'til Leather tape and got voted No. 1 guitarist in your magazine." On Megadeth's 1985 debut album Killing Is My Business... and Business Is Good!, Mustaine included the song "Mechanix", which Metallica renamed as "The Four Horsemen" on Kill 'Em All. Mustaine said he did this to "straighten Metallica up", as Metallica referred to Mustaine as a drunk and said he could not play guitar. Metallica's first show with Hammett was on April 16, 1983, at the nightclub The Showplace in Dover, New Jersey.

Metallica's third studio album, Master of Puppets was recorded at Sweet Silence Studios and was released in March 1986. The album peaked at number 29 on the Billboard 200, and spent 72 weeks on the chart. The album was the band's first to be certified gold on November 4, 1986, and was certified six times platinum in 2003. Steve Huey of Allmusic considered the album "the band's greatest achievement". Following the release of the album, Metallica supported Ozzy Osbourne for a United States tour. Hetfield broke his wrist skateboarding down a hill and continued the tour performing vocals, with guitar technician John Marshall playing rhythm guitar.

On September 27, 1986, during the European leg of Metallica's Damage, Inc. Tour, members drew cards to see which bunk of the tour bus they would sleep in. Burton won and chose to sleep in Hammett's bunk. Around dawn near Dörarp, Sweden, the bus driver lost control and skidded, which caused the bus to flip several times. Ulrich, Hammett, and Hetfield sustained no serious injuries; however, bassist Burton was pinned under the bus and was killed. Hetfield recalls, "I saw the bus lying right on him. I saw his legs sticking out. I freaked. The bus driver, I recall, was trying to yank the blanket out from under him to use for other people. I just went, 'Don't fucking do that!' I already wanted to kill the bus driver. I don't know if he was drunk or if he hit some ice. All I knew was, he was driving and Cliff wasn't alive anymore." Burton's death left Metallica's future in doubt. The three remaining members decided that Burton would want them to carry on, and with the Burton family's blessings, the band sought a replacement.

Roughly 40 people tried out for auditions including Hammett's childhood friend Les Claypool of Primus, Troy Gregory of Prong, and Jason Newsted, formerly of Flotsam and Jetsam. Newsted learned Metallica's entire setlist, and after the audition Metallica invited him to Tommy's Joynt in San Francisco. Hetfield, Ulrich, and Hammett decided that Newsted was the one to replace Burton, and Newsted's first live performance with Metallica was at the Country Club in Reseda, California. The members took it on themselves to "initiate" Newsted by tricking him into eating a ball of wasabi.

…And Justice for All, the group's first studio album since Burton's death, was released in 1988. The album was a commercial success, peaking at number six on the Billboard 200, the band's first album to enter the top 10. The album was certified platinum nine weeks after its release. Newsted's bass was purposely turned down on the album as a part of the continuous "hazing" he received, and his musical ideas were ignored (However, he did receive a writing credit on track one, "Blackened"). There were complaints with the production; namely, Steve Huey of Allmusic noted Ulrich's drums were clicking more than thudding, and the guitars "buzz thinly". The Damaged Justice tour followed to promote the album.

In October 1990, Metallica entered One on One studio in North Hollywood to record its next album. Bob Rock, who had worked with the bands The Cult, Bon Jovi, and Mötley Crüe, was hired as the producer. Metallica (also known as "The Black Album") was remixed three times, cost $1 million, and ended three marriages. Although the release was stalled until 1991, Metallica debuted at number one on the Billboard 200, selling 650,000 units in its first week. The album was responsible for bringing Metallica to the attention of the mainstream and has been certified 15 times platinum in the United States, which makes it the 26th highest-selling album in the country. The making of Metallica and the following tour was documented in A Year and a Half in the Life of Metallica. Dubbed the Wherever We May Roam Tour, it lasted 14 months and included dates in the United States, Japan, and the UK. In April 1992, Metallica appeared at the Freddie Mercury Tribute Concert, performing a two-song set. Hetfield later performed "Stone Cold Crazy" with the remaining members of Queen and Tony Iommi.

On August 8, 1992, during the co-headlining Guns N' Roses/Metallica Stadium Tour with Guns N' Roses, Hetfield suffered second and third degree burns to his arms, face, hands, and legs. There was confusion with the new pyrotechnics setup, which resulted with Hetfield walking into a 12-foot (3.7 m) flame during "Fade to Black". Newsted recalls Hetfield's skin was "bubbling like on The Toxic Avenger". Guitar technician John Marshall, who had previously filled in on rhythm guitar and was now playing in Metal Church, replaced Hetfield for the remainder of the tour as Hetfield was unable to play guitar, although he was able to sing. The band's first box set was released in November 1993 called Live Shit: Binge & Purge. The collection contained three live CDs, three home videos, and a book filled with riders and letters.

After almost three years of touring to support Metallica, including a headlining performance at Woodstock '94, Metallica returned to the studio to write and record its sixth studio album. The band took a break in the summer of 1994 and played three outdoor shows which included headlining Donington Park in the United Kingdom, supported by Slayer, Skid Row, Slash's Snakepit, Therapy?, and Corrosion of Conformity. The short tour was titled Escape From The Studio '95. The band spent roughly one year writing and recording new songs, resulting in the release of Load in 1996, which entered the Billboard 200 and ARIA Charts at number one, marking the band's second number one. The cover of Load was created by Andres Serrano, and was called Blood and Semen III. Serrano pressed a mixture of his own semen and bovine blood between sheets of plexiglass. The release marked a change in musical direction for the band and a new look with band members receiving haircuts. Metallica headlined the alternative rock festival Lollapalooza in the summer of 1996.

In 2000, Metallica discovered that a demo of its song "I Disappear", which was supposed to be released in combination with the Mission: Impossible II soundtrack, was receiving radio airplay. Tracing the source of the leak, the band found the file on the Napster peer-to-peer file-sharing network, and also found that the band's entire catalogue was freely available. Legal action was initiated against Napster with Metallica filing a lawsuit at the U.S. District Court, Central District of California, alleging that Napster violated three areas of the law: copyright infringement, unlawful use of digital audio interface device, and the Racketeer Influenced and Corrupt Organizations Act (RICO).

As plans were being made to enter the recording studio, Newsted left the band on January 17, 2001. His statement revealed his departure was based on "private and personal reasons, and the physical damage I have done to myself over the years while playing the music that I love." During a Playboy interview with Metallica, Newsted revealed intentions he wanted to release an album with his side project, Echobrain. Hetfield was against the idea and said, "When someone does a side project, it takes away from the strength of Metallica" and a side project is "like cheating on your wife in a way". Newsted countered his statement by saying Hetfield recorded vocals for a song in the film South Park: Bigger, Longer & Uncut, and appears on two Corrosion of Conformity albums. Hetfield replied, "My name isn't on those records. And I'm not out trying to sell them", and pondered questions such as, "Where would it end? Does he start touring with it? Does he sell shirts? Is it his band?"

In December 2006, Metallica released a DVD containing all the music videos from 1989 to 2004. The DVD, titled The Videos 1989–2004, sold 28,000 copies in its first week, and entered the Billboard Top Videos chart at number three. Metallica recorded a cover of Ennio Morricone's "The Ecstasy of Gold" for a tribute album titled We All Love Ennio Morricone, released in February 2007. The cover received a Grammy nomination at the 50th Grammy Awards for the category "Best Rock Instrumental Performance". A recording of "The Ecstasy of Gold" has been played as the introduction for Metallica performances since the 1980s. However, this new version features the band itself performing the piece, giving a new guitar-based interpretation to the music.

In 2006, Metallica announced on its official website that after 15 years, long-time producer Bob Rock was stepping down and would not be producing Metallica's next studio album. Metallica chose to work with producer Rick Rubin, who has produced albums for the bands Danzig, Johnny Cash, Slayer, Slipknot and System of a Down. Metallica set the release date for the album Death Magnetic as September 12, 2008, and they filmed a music video for the first single "The Day That Never Comes".

On November 9, 2010, Metallica announced that they will be headlining the Rock in Rio, in Rio de Janeiro, on September 25, 2011.

In a November 2010 interview with The Pulse of Radio, Ulrich stated that Metallica wants to get back to writing again for 2011. Ulrich stated: "There’s a bunch of balls in the air for 2011, but I think the main one is we really want to get back to writing again. We haven’t really written since, what, ’06, ’07, and we want to get back to kind of just being creative again. Right now we are going to just chill out and then probably start up again in, I’d say, March or April, and start probably putting the creative cap back on and start writing some songs."

Influenced by early heavy metal and hard rock bands such as Black Sabbath, Deep Purple, Led Zeppelin and Scorpions, New Wave of British Heavy Metal bands such as Venom, Motörhead, Diamond Head, Judas Priest, and Iron Maiden, and early Punk Rock bands such as The Ramones, The Sex Pistols, and The Misfits, early Metallica releases contained fast tempos, harmonized leads, and nine-minute instrumentals. Steve Huey of Allmusic said that Ride the Lightning featured "extended, progressive epics; tight, concise groove-rockers". Huey felt Metallica expanded its compositional technique and range of expression to take on a more aggressive approach in following releases, and lyrics dealt with more personal and socially conscious issues. Lyrical themes explored on Master of Puppets included religious and military leaders, rage, insanity, monsters, and drugs.

In 1991, with new producer Bob Rock, Huey felt Metallica simplified and streamlined its music for a more commercial approach to appeal to the mainstream audience. The band abandoned its aggressive, fast tempos to expand its music and expressive range, said Robert Palmer of Rolling Stone. The change in direction proved commercially successful as Metallica was the band's first album to peak at number one on the Billboard 200. Metallica noticed changes to the rock scene created by the grunge movement of the early 1990s. In what has been described as "an almost alternative rock" approach, the band focused on non-metal influences and changed musical direction. Moving away from lyrical themes dealing with drugs and monsters, Metallica's new lyrical approach focused on anger, loss, and retribution. Some fans and critics were not pleased with this change, which included haircuts, the cover of Load, and headlining the alternative rock concert Lollapalooza. David Fricke of Rolling Stone described the move as "goodbye to the moldy stricture and dead-end Puritanism of no-frills thrash" and called Load the heaviest record of 1996. With the release of ReLoad in 1997, the band displayed more blues and early hard rock influences, incorporating more rhythm and harmony in song structures.

St. Anger marked another large change in the band's sound. Guitar solos were omitted from the album, leaving a "raw and unpolished sound". The band used drop C tuning, and Ulrich's snare drum received particular criticism. New York Magazine's Ethan Brown noted it "reverberates with a thwong". Lyrics on the album dealt with Hetfield's stint in rehab, including references to the devil, anti-drug themes, claustrophobia, impending doom, and religious hypocrisy. At the advice of producer Rick Rubin, for their ninth studio album, Death Magnetic, the band returned to E tuning (though all songs were tuned half step down live) and guitar solos, and adapted Middle Eastern influences.