21st Century Breakdown is the eighth studio album by American rock band Green Day, released on May 15, 2009, through Reprise Records. Green Day commenced work on the record in January 2006 and forty-five songs were written by vocalist/guitarist Billie Joe Armstrong by October 2007, but the band members did not enter studio work until January 2008. The album is a rock opera much like their previous album American Idiot (2004). Armstrong has described the album as a "snapshot of the era in which we live as we question and try to make sense of the selfish manipulation going on around us, whether it be the government, religion, media or frankly any form of authority". The singles "Know Your Enemy" and "21 Guns" exemplify the themes of alienation and politically motivated anger present in the record. To handle the record, they turned to producer Butch Vig, best known for producing Nirvana's Nevermind (1991). Critical response to 21st Century Breakdown was generally positive. The record achieved Green Day's best chart performance to date, reaching number one on the album charts of various countries, including the United States Billboard 200, the European Top 100 Albums, and the United Kingdom Albums Chart. The album won the Grammy Award for Best Rock Album at the 52nd Grammy Awards on January 31, 2010. As of December 2010, 21st Century Breakdown has sold 1,005,000 copies in the United States and more than 4 million worldwide. Writing and recording Green Day began to write new songs for what would become 21st Century Breakdown in January 2006 after touring extensively in 2005 in support of their seventh studio album American Idiot. At the time, frontman Billie Joe Armstrong stated: "We'll start with silence, and that's how we'll be able to find the inspiration to find another record." The band did not release any details of the writing and recording process until October 2007, when Armstrong said in an interview with Rolling Stone that he had written "something like 45 songs". The band members worked on the primitive conceptual stages of the album at their rehearsal studio in Oakland, California. Little was revealed on the themes or musical style of the album, but Armstrong stated: "I want to dig into who I am and what I'm feeling at this moment – which is middle-aged." He added that many of the 45 songs were written on piano instead of guitar.