Under My Skin is the second studio album by Canadian singer-songwriter Avril Lavigne, released worldwide on May 25, 2004; It was her last album with Arista Records. Under My Skin debuted at number-one on the Billboard 200 albums chart and according to Billboard magazine, was ranked number 149 on the list of top-selling album of the 2000s. It has sold more than 10 million copies worldwide.

Having no plans of working with producers or professional writers, Lavigne wrote much of the album with Canadian singer-songwriter Chantal Kreviazuk, with whom she had developed a friendship in the summer of 2003. Kreviazuk, whose husband Raine Maida's band Our Lady Peace opened for Lavigne's concert in Europe, introduced herself at an after-party for the SARS benefit concerts held in Toronto in June 2003. The following day, Lavigne and Kreviazuk ate lunch together, during when Lavigne shared how she wanted the development of the album to be. They wrote songs for almost three weeks at Maida's warehouse in Toronto. Kreviazuk invited Lavigne to continue working in a Malibu, California house she shared with Maida, which contained a recording studio. Many of the tracks in the album were recorded in Malibu.

Avril Ramona Lavigne (pronunciation: /ˈævrɨl ləˈviːn/; AV-ril lə-VEEN; born 27 September 1984) is a Canadian singer-songwriter. She was born in Belleville, Ontario, but spent most of her youth in the small town of Napanee. By the age of 15, she had appeared on stage with Shania Twain; by 16, she had signed a two-album recording contract with Arista Records worth more than $2 million. In 2002, when she was 17 years old, Lavigne broke onto the music scene with her debut album Let Go.

Let Go made Lavigne the youngest female soloist to reach No. 1 in the UK, and the album was certified four-times platinum by the Recording Industry Association of America. By 2009, over 16 million copies had been sold worldwide. Her breakthrough single, "Complicated", peaked at No. 1 in many countries around the world, as did the album Let Go. Her second album, Under My Skin, was released in 2004 and was her first album to peak at No. 1 on the U.S. Billboard 200, eventually selling more than 10 million copies worldwide. The Best Damn Thing, Lavigne’s third album, was released in 2007, becoming her third No. 1 album in the UK Albums Chart and featuring her first U.S. Billboard Hot 100 No. 1 single, "Girlfriend". Lavigne has scored six number-one singles worldwide, including "Complicated", "Sk8er Boi", "I'm with You", "My Happy Ending", "Nobody's Home", and "Girlfriend". With more than 30 million copies of her albums sold worldwide, Lavigne is one of the top-selling artists releasing albums in the U.S., with over 10.25 million copies certified by the RIAA. Her fourth studio album, Goodbye Lullaby, was released in March 2011. Goodbye Lullaby gave Lavigne her fourth top 10 album on the U.S. Billboard 200 and the UK Albums Chart and her third No. 1 album in both Japan and Australia. Three months after the release of Goodbye Lullaby, Lavigne began work on her fifth album, which will be released on Epic Records following her departure from RCA Records.

Under My Skin may refer to:

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