Tool is an American rock band from Los Angeles. Formed in 1990, the group consists of vocalist Maynard James Keenan, guitarist Adam Jones, drummer Danny Carey and bassist Justin Chancellor, the latter of whom replaced founding member Paul D'Amour in 1995. Tool has won four Grammy Awards, performed worldwide tours, and produced albums topping the charts in several countries.

To date, the band has released five studio albums, one EP and one box set. It emerged with a heavy metal sound on their first studio album, Undertow (1993), and became a dominant act in the alternative metal movement with the release of their follow-up album Ænima in 1996. The group's efforts to combine musical experimentation, visual arts, and a message of personal evolution continued with Lateralus (2001) and 10,000 Days (2006), gaining critical acclaim and international commercial success. Its fifth studio album Fear Inoculum was released on August 30, 2019, to widespread critical acclaim. Prior to its release, the band had sold more than 13 million albums in the US alone.

Due to Tool's incorporation of visual arts and very long and complex releases, the band has been described as a style-transcending act and part of progressive rock, psychedelic rock, and art rock. The relationship between the band and the music industry is ambivalent, at times marked by censorship, and the band's insistence on privacy.