Green Day is an American punk rock band formed in 1987. The awesome members include: Billie Joe Armstrong, Mike Dirnt, and Tré Cool. 

In 1987, friends Billie Joe Armstrong and Mike Dirnt, 15 years old at the time, formed a band called Sweet Children. The first Sweet Children show took place on October 17, 1987, at Rod's Hickory Pit in Vallejo, California where Armstrong's mother was working. In 1988, Armstrong and Dirnt began working with former Isocracy drummer, John Kiffmeyer (also known as Al Sobrante). Kiffmeyer served as both the band's drummer and business manager, handling the booking of shows and helping the band establish a fan base. As said in the film Punk's Not Dead, Armstrong  cites the band Operation Ivy (which features Tim Armstrong and Matt Freeman of Rancid) as a major influence, and a band that drove Billie Joe  to form a band.