Green Day is an American punk rock band formed in 1986 by vocalist/guitarist Billie Joe Armstrong and bassist Mike Dirnt. For much of their career, the band has been a trio with drummer Tré Cool, who replaced former drummer John Kiffmeyer in 1990 prior to the recording of the band's second studio album, Kerplunk (1992). In 2012, guitarist Jason White became a full-time member after having performed with the band as a session and touring member since 1999.

Green Day was originally part of the punk scene at the DIY 924 Gilman Street club in Berkeley, California. The band's early releases were with the independent record label Lookout! Records. In 1994, its major label debut Dookie (released through Reprise Records) became a breakout success and eventually sold over 10 million copies in the U.S. Green Day was widely credited, alongside fellow California punk bands Sublime, Bad Religion, The Offspring and Rancid, with popularising and reviving mainstream interest in punk rock in the United States.

Green Day's three follow-up albums, Insomniac (1995), Nimrod (1997), and Warning (2000) did not achieve the massive success of Dookie, though they were still successful, with Insomniac and Nimrod reaching double platinum and Warning achieving gold status. The band's rock opera, American Idiot (2004), reignited the band's popularity with a younger generation, selling five million copies in the U.S. The band's eighth studio album, 21st Century Breakdown, was released in 2009 and achieved the band's best chart performance to date. 21st Century Breakdown was followed up by a trilogy of albums called ¡Uno!, ¡Dos!, and ¡Tré!, which were released in September, November and December of 2012 respectively.

They are one of the world's best-selling bands of all time, having sold more than 75 million records worldwide. The group has won five Grammy Awards: Best Alternative Album for Dookie, Best Rock Album for American Idiot, Record of the Year for "Boulevard of Broken Dreams", Best Rock Album for the second time for 21st Century Breakdown and Best Musical Show Album for American Idiot: The Original Broadway Cast Recording. In 2010, a stage adaptation of American Idiot debuted on Broadway. The musical was nominated for three Tony Awards: Best Musical, Best Scenic Design and Best Lighting Design, losing only the first. Also in 2010, Green Day were ranked no. 91 in the VH1 list of the "100 Greatest Artists of All Time". On April 18, 2015, the band was inducted into the Rock and Roll Hall of Fame as a part of the 2015 class, in their first year of eligibility.