Nimrod is the fifth studio album by the American punk rock band Green Day, released on October 14, 1997 through Reprise Records. The group began work on the album in the wake of their cancellation of a European tour after the release of Insomniac (1995). Recorded at Conway Studios in Los Angeles, the album was written with the intent of creating a set of stand-alone songs as opposed to a cohesive album. Retrospectively, Nimrod is noted for it's musical diversity and experimentation. It contains elements of folk, surf rock, and ska; the lyrical themes discussed on the record include maturity, personal reflection, and fatherhood. Nimrod has sold over 10 million copies worldwide.