Fall Out Boy is an American pop punk band from Wilmette, Illinois (a suburb of Chicago), that formed in 2001. The band consists of Patrick Stump (lead vocals, rhythm guitar, primary composer), Pete Wentz (bass guitar, backing vocals, primary lyricist), Joe Trohman (lead guitar), and Andy Hurley (drums, percussion).

Fall Out Boy has won several awards for its album From Under the Cork Tree. Released in 2005, the album has achieved double platinum status after selling more than 2.5 million albums in the United States. In support of the album, Fall Out Boy headlined tours in 2005 and the year before 2007 in the United States, Canada, Japan, and Europe.

In February 2007, the band released Infinity on High to major chart success, reaching #1 on the Billboard 200 and selling 260,000 copies in its first week. The first single, "This Ain't a Scene, It's an Arms Race", reached #1 on the Pop 100 and #2 on the Billboard Hot 100. To promote the album, the band performed at the Live Earth concerts July 7, headlined the Honda Civic Tour through mid-2007, and the band performed at the MTV Video Music Awards on September 9. The band has toured numerous times, most recently on the Young Wild Things Tour with the Plain White T's, Gym Class Heroes, and Cute Is What We Aim For.

On December 16, 2008, the band will release its fifth studio album, Folie à Deux. The lead single for the album, "I Don't Care" was released on September 3, 2008, and the song is currently on its chart run.

Fall Out Boy was formed in early 2001 by friends Joe Trohman and Pete Wentz. The two had played in various bands in the Chicago area. They decided they wanted to start a band that was similar to bands they listened to growing up such as Green Day, Descendents, and The Smiths. Trohman met high schooler Patrick Stump in a Borders Bookstore. Trohman introduced himself to Stump when he overheard him talking about the band Neurosis, in which they shared a mutual interest.

Stump auditioned as a drummer, but as soon as his vocal range was discovered, he became the lead singer. Two other Chicago musicians were recruited; T.J. Raccine on guitar and a drummer simply credited as Mike. The following year, the band debuted with a self-released demo and followed it up with the May 28, 2002 release of Split EP, which featured Project Rocket, on Uprising Records. The group released a mini-LP, Fall Out Boy's Evening Out with Your Girlfriend, on Uprising Records, in 2003.

The band was nameless for its first two shows. At the end of the second show, it asked the audience to yell out ideas for a name. One audience member suggested "Fallout Boy," a reference to the sidekick of the Simpsons cartoon character Radioactive Man.

While widely considered to be a pop punk band, Fall Out Boy is often described as emo and cites emo group The Get Up Kids as an influence. Pete Wentz was interviewed for a retrospective article in Alternative Press when The Get Up Kids disbanded in 2005, and stated that "Fall Out Boy would not be a band if it were not for the Get Up Kids." Fall Out Boy's main songwriters are Patrick Stump (melody) and Pete Wentz (lyrics), though they traditionally credit the whole band as songwriters.

Their albums Take This To Your Grave and From Under The Cork Tree are both said to have pop punk as well as punk rock sounds and influences, and their latest work, Infinity on High, features a wide range of styles and instrumentation, including orchestral and choral arrangements ("Thnks fr th Mmrs", "You're Crashing, But You're No Wave") and a slower piano ballad ("Golden").
The band has shown signs of experimentation, working with hip hop producers and artists, including Timbaland, Lil Wayne and Kanye West, and have also been influenced by R&B music.

In general, the group has direct ties to melodic pop music, with Patrick Stump becoming a producer aside from his work with the band, and they also are closely connected to hardcore punk, as evident in their use of throat vocals and their prior involvement in the underground Chicago music scene. Moreover, a central part of Fall Out Boy's sound is rooted in the band's lyrics, mainly penned by bassist Pete Wentz, who commonly uses irony and other literary devices to narrate personal experience and stories.