Green Day is an American rock band formed in the East Bay of California in 1987 by lead vocalist and guitarist Billie Joe Armstrong, together with bassist and backing vocalist Mike Dirnt. In 1994, their major-label debut Dookie became a breakout success and eventually shipped over 10 million copies in the U.S. Alongside fellow California punk bands Bad Religion, the Offspring, Rancid, Pennywise and Social Distortion, Green Day is credited with popularizing mainstream interest in punk rock in the U.S.