"Parabola" is a song by the American rock band Tool. The song was released as the second single from their third studio album Lateralus. Initially released in 2002 as a promo only, the single was re-released on December 20, 2005, which includes the song and a DVD containing the music video and an optional "dual" audio commentary on the video by Jello Biafra of Dead Kennedys. The dual commentary consists of two separate recordings of Biafra's voice, one playing in each stereo channel. The DVD was released alongside a DVD single for "Schism" as well. The song uses a modified drop-B tuning for the guitars.