SOUR is the debut studio album by American singer-songwriter Olivia Rodrigo. It was released on May 21, 2021, by Geffen Records. The album was written by Rodrigo and her producer Dan Nigro. Originally planned as an EP, Sour was expanded into a full-length album following the viral success of her debut single, "Drivers License".
 
Influenced by Rodrigo's favorite genres and singer-songwriters, Sour is primarily a pop record that spans from energetic pop-punk songs to bedroom pop ballads. Its subject matter centers on adolescence, failed romance, and heartache. She said the album explores her perils and discoveries as a 17-year-old, with its title referring to the "sour" emotions young people experience but are often criticized for, such as anger, jealousy, and unhappiness.