Tool was created in 1990 by singer Maynard James Keenan and guitarist Adam Jones. Keenan and Jones met in 1989, and over the next couple years they met and recruited drummer Danny Carey and bassist Paul D'Amour into the band. Tool spent its first couple years playing the local Los Angeles circuit before being signed by label Zoo Entertainment. The band began their meteoric rise to fame with their 1992 debut EP, Opiate. In 1993, the band released their first studio album, Undertow, at the height of the alternative rock movement in the United States. After landing a spot in the main stage lineup at the 1993 Lollapalooza, sales of the album began to skyrocket, and by September of that year, it was certified platinum. The release of Undertow was not without controversy. The album's cover, depicting a nude man and woman, was pulled from several retail locations, prompting the band to release another version with a censored cover. Regardless of the controversy, sales of the album continue to do well, selling well over two million copies since its release.

Paul D'Amour left the band in 1995 and was replaced by Justin Chancellor, giving the band their current line-up. With a new member, Tool went back to the studio. According to All Music Guide, the tastes of music listeners had changed by the time the quartet released their sophomore effort Ænima in 1996, moving from alternative rock to metal. However, the album defied the transition, landing at #2 on the Billboard 200 and selling well over 3 million copies since the release. The album was dedicated to and partially themed around comedian Bill Hicks, with whom the band developed a friendship before the former died of pancreatic cancer in 1994. Two songs from the album, "Third Eye" and "Ænema," both make references to Hicks material, and a special cover prominently features the comedian. With the outstanding success of their first two albums, the band's fortunes seemed bright.

However, a long hiatus following Tool's promotional tour for Ænima, including a headlining spot at the 1997 Lollapalooza, left questions about the future of the band. Keenan formed a side project, A Perfect Circle, which released the #4 charting Mer de Noms in 2000. The band was able to disspell rumors of a breakup by releasing a box set, Salival in 2000. They followed up with their third album Lateralus in 2001. Clocking in at #1 and achieving double platinum status, the album gave Tool not only their biggest hit album to date, but also one of their biggest singles, when "Schism" reached #2 on the U.S. Modern Rock chart. After taking another extended break, the band released their latest album, 10,000 Days. Though the 2006 album was less well received than the band's previous work, according to Metacritic, it has still been commercially successful, reaching #1 on the Billboard 200, selling over a million units, and spawning the hit single "Vicarious."