Under My Skin is the second studio album by Canadian singer-songwriter Avril Lavigne that was released through the RCA Records Label internationally throughout May 2004. Lavigne wrote most of the album with singer-songwriter Chantal Kreviazuk, who invited her to a Malibu in-house recording studio shared by Kreviazuk and her husband Raine Maida, where Lavigne recorded many of the songs. The album was produced by Maida, Don Gilmore, and Butch Walker.
Under My Skin debuted at number-one on the U.S. Billboard 200 albums chart and according to Billboard magazine, was ranked number 149 on the list of top-selling albums of the 2000s. It has sold more than 12 million copies worldwide, 3 million of which were sold in the United States, ranking the album No. 149 on the Billboard 200 Decade End Chart. Because of the album's darker vibe reminiscent of post-grunge, nu metal[A] and more melodic rocker songs, it received generally positive reception from critics.