Sour (stylized in all caps) 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 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 melodramatic alternative pop, bedroom pop, pop rock, and teen pop record with elements of alternative rock, dream pop, folk-pop, pop-punk, and synth-pop, spanning from angsty guitar-driven rockers to melancholic acoustic balladry. 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, including anger, jealousy, and unhappiness. Sour was the first debut album to produce two number-one debuts on the US Billboard Hot 100: "Drivers License" and "Good 4 U". The singles "Deja Vu" and "Traitor" entered the top 10. Sour broke the global Spotify record for the biggest opening week for an album by a female artist. It topped the charts in several countries, including the US Billboard 200, and was one of the best-selling albums of 2021. Sour was praised by music critics, who regarded it as a strong debut album, underscoring Rodrigo's realistic lyrics and appeal to Gen Z listeners. Various publications listed it among the best albums of 2021, including Billboard and Rolling Stone that placed the album at number one on their year-end rankings. At the 64th Annual Grammy Awards, Sour and "Drivers License" won Best Pop Vocal Album and Pop Solo Performance, respectively; Rodrigo won Best New Artist as well. A YouTube concert film and a Disney+ documentary, titled Sour Prom and Driving Home 2 U respectively, supplement the album. Rodrigo embarked on the Sour Tour, her first headlining concert tour, from April to July 2022. In 2023, it was ranked number 358 on Rolling Stone's list of the "500 Greatest Albums of All Time".