Green Day is a punk rock band which formed in the East Bay, California, United States in 1987. They consist of Billie Joe Armstrong (vocals, guitar), Mike Dirnt (bass, vocals; born Michael Pritchard) and Tré Cool (drums; born Frank Edwin Wright III). Jason White has played second guitar when the band performs live since 2000 (and is considered to be the unofficial fourth member of the band, to the point where he's appeared in several of the band's music videos since 2004), and Jason Freese is the band's live keyboardist.

Billie Joe and Mike began the band under the name Sweet Children near ]San Francisco, California in 1987. In 1988, they changed the band's name to Green Day. After the original drummer Al Sobrante (John Kiffmeyer) left for college in 1991, Tré Cool joined the band. Green Day released two albums, 1,039/Smoothed Out Slappy Hours and Kerplunk! with Lookout! Records before their breakthrough album, Dookie, was released in 1994 under Reprise Records. Just before this release however, many feared the end of Green Day as Billie Joe was at the time spending more and more time playing in his Status Quo tribute band "Status Joe."

Dookie was certified diamond (10 million copies shipped) in the United States. Their second best-selling album, American Idiot, released in 2004, has sold over eleven million copies worldwide, and won the 2005 Grammy Award for "Best Rock Album". In 2005 Green Day swept the MTV Video Music Awards, winning seven out of eight nominations: "Video of the Year," "Best Rock Video," "Best Group Video," "Best Direction," "Best Editing," "Best Cinematography" (all of which were for Boulevard of Broken Dreams), and the "Viewer's Choice Award" for American Idiot. In addition to their American Music Award wins for "Favorite Alternative Artist" and "Favorite Pop/Rock Album" for American Idiot, Green Day won the 2006 Grammy Award for Record of the Year for "Boulevard of Broken Dreams."

Green Day went back into the studio and recorded a medley with U2, which was performed on September 25th at the re-opening of the Superdome in New Orleans, Louisiana. Songs consisted of Wake Me Up When September Ends, The Saints Are Coming and Beautiful Day.

Recently, Green Day has headed back into the studio to record their 8th studio album. The record is surprisingly being produced by Butch Vig instead of Rob Cavallo. This album is more..."religious", and is influenced by Bob Dylan, Bruce Springsteen, and The Beatles, to name a few. The album has been voted most anticipated album of 2009 by APM (Alternative Press Magazine).

The new album, entitled 21st Century Breakdown, will be released in May 2009.