Green Day is an influential American rock band formed in 1987 in Berkeley, California. The group originally consisted of Billie Joe Armstrong as lead vocalist and guitarist, Mike Dirnt on bass and backing vocals, and Al Sobrante (John Kiffmeyer) on drums. However, in 1990, Sobrante was replaced by Tré Cool, solidifying the lineup that would catapult the band to international fame. Emerging from the punk rock scene of the 924 Gilman Street club in Berkeley, Green Day started gaining attention with their early releases on the independent label Lookout Records. Their first two albums, including *39/Smooth* (1990) and *Kerplunk* (1991), built a loyal underground following. The band's breakthrough came with their major-label debut, *Dookie* (1994), released on Reprise Records. Fueled by fast-paced, energetic tracks like "Basket Case," "Longview," and "When I Come Around," the album became a global phenomenon, selling over 20 million copies and earning a Grammy Award for Best Alternative Album. Green Day continued their success with albums like *Insomniac* (1995), *Nimrod* (1997), and *Warning* (2000), showcasing both their punk roots and evolving musical style. However, it was their politically charged rock opera, *American Idiot* (2004), that revitalized their career and cemented their status as one of the defining bands of their generation. The album, featuring hits like "American Idiot," "Boulevard of Broken Dreams," and "Holiday," addressed themes of disillusionment and angst in post-9/11 America. It won a Grammy for Best Rock Album and was later adapted into a successful Broadway musical. Green Day's innovative approach and consistent reinvention have allowed them to remain relevant decades into their career. Subsequent releases such as *21st Century Breakdown* (2009), *Revolution Radio* (2016), and *Father of All...* (2020) further demonstrated their ability to combine raw punk energy with sophisticated storytelling. Inducted into the Rock and Roll Hall of Fame in 2015, Green Day has become one of the best-selling music acts of all time, with over 75 million records sold worldwide. Renowned for their explosive live performances and enduring influence on punk and alternative rock, the band has left an indelible mark on music and popular culture.