Hybrid Theory is the debut album by the American rock band Linkin Park, and the album's lyrical themes deal with problems lead vocalist Chester Bennington experienced during his adolescence, including drug abuse and the constant fighting and divorce of his parents. Hybrid Theory takes its title from the previous name of the band as well as the concept of music theory and combining different styles. Four singles were released from the album: "One Step Closer," "Crawling," "Papercuts," and "In the End," all of them being responsible for launching Linkin Park into mainstream popularity.