In the Zone is the fourth studio album by American singer Britney Spears. It was released on November 15, 2003, by Jive Records. Spears began writing songs during her Dream Within a Dream Tour, not knowing the direction of the record. She stated she was an autobiographical songwriter, although not to the point where she felt self-exploited. During the process, she ended her highly-publicized relationship with singer Justin Timberlake. With the tour's conclusion in July 2002, Spears planned to take a six-month break from her career; however, recording for the album commenced in November.

For In the Zone, Spears experimented with different producers, trying to find those with whom she had chemistry. She collaborated with artists such as Madonna and the Ying Yang Twins, while contributions came from a wide range of producers, including Bloodshy & Avant, R. Kelly, Trixster, Moby, Guy Sigsworth and the Matrix. Their final result was an eclectic record incorporating pop and urban music styles with instrumentation from techno and Middle Eastern genres. Its lyrical themes range from romance and partying to more explicit ones such as sex and masturbation. Spears explained that the album's sexual nature was subconscious and emerged while she was in the process of developing the album.

In the Zone received positive reviews upon its release, with music critics widely praising its innovative production, aesthetics, lyricism and blend of eclectic genres, though some criticized Spears' vocals on certain tracks for being distant and processed. A global commercial success, it debuted atop the US Billboard 200 with first-week sales of 609,000 copies, making Spears the first female artist to have her first four albums reach number one. Retrospectively, the album is widely considered a major turning point in Spears' artistic journey and a culmination in her transition from a teen pop star to a more adult artist. Various critics have considered it the album that pushed Spears past her contemporaries and establishing her as the definitive female artist of the 2000s.

In the Zone was promoted with four singles. "Me Against the Music", featuring Madonna, reached the top ten in nearly every country except the United States, where it only peaked at number 35 on the Billboard Hot 100. "Toxic" peaked atop the charts in eight countries and at number nine on the Billboard Hot 100, becoming Spears' first US top-ten hit since "Oops!... I Did It Again" (2000), and won Spears her first Grammy Award. "Everytime" peaked at number 15 on the US Billboard Hot 100 and within the top ten nearly everywhere else. "Outrageous" was plagued by a lack of promotion due to Spears injuring her knee while filming its accompanying music video, and only peaked at number 79 on the US Billboard Hot 100. To further promote the album, Spears embarked on the Onyx Hotel Tour (2004).