Nothing was ever quite the same after Nirvana. The band's second album, 1991's Nevermind, revolutionized popular music by bringing alternative rock above ground, introducing mainstream audiences to sounds and concepts that had previously existed only in shadowy record store corners and on low-frequency college radio airwaves. Nevermind's noisy, dissonant guitar rock, mumbled or howled surrealistic lyrics, and generally angsty punk attitudes were unlikely candidates for chart success, but the band undercut their grungy songs with enough pop melodicism to create a sound unlike anything average listeners had ever heard before, striking at the exact right moment to become an unprecedented success.