B'Day is the second studio album by American singer and songwriter Beyoncé. It was released on September 1, 2006, by Columbia Records, Music World Entertainment and Sony Urban Music. The album was recorded in April 2006, and was produced by Beyoncé herself, alongside Darkchild, Nellee Hooper, Ne-Yo, The Neptunes, Stargate, and Swizz Beatz, among others. The album features two guest appearances from Beyoncé's fiancé Jay-Z, with deluxe and international editions including Bun B of UGK, Slim Thug, Shakira, and Alejandro Fernández.

Originally set to be released in 2004, B'Day was planned as a follow-up to Beyoncé's solo debut Dangerously in Love (2003). However, it was delayed to accommodate the recording of Destiny's Child's final studio album Destiny Fulfilled (2004) and Beyoncé's starring role in the film Dreamgirls (2006). While on vacation after filming Dreamgirls, Beyoncé began contacting various producers and rented Sony Music Studios, completing the album within two weeks during April 2006. Most of the lyrical content of the album was inspired by Beyoncé's role in the film, with its musical style ranging from 1970s–1980s funk influences and balladry to urban contemporary elements such as hip hop, pop, and R&B. Live instrumentation was employed in recording most of the tracks as part of Beyoncé's vision of creating a record using live instruments.

Upon its release, B'Day received generally favorable reviews from music critics, who directed most of the acclaim towards its sonic quality and Beyoncé's vocal performance. A commercial success, the album debuted atop the US Billboard 200, selling over 541,000 copies in its first week. Among numerous additional accolades, it won Best Contemporary R&B Album at the 49th Annual Grammy Awards (2007). B'Day Anthology Video Album, which featured 13 music videos to accompany the album's tracks, was released alongside the album's reissue, subtitled Deluxe Edition, in April 2007. B'Day has been certified quintuple platinum by the Recording Industry Association of America (RIAA) and, as of 2013, has sold over 8 million copies worldwide.

B'Day produced six singles. "Déjà Vu" peaked at number four on the US Billboard Hot 100, while "Ring the Alarm" became Beyoncé's highest-debuting single at the time but broke her string of top-ten singles after peaking at number 11. "Irreplaceable" became her fourth Billboard Hot 100 number-one, while the deluxe track "Beautiful Liar" peaked at number three. Both singles achieved widespread international success. "Get Me Bodied" was released exclusively in the United States, while "Green Light" was released internationally; neither replicated the success of their predecessors. To further promote B'Day, Beyoncé embarked on her second solo concert tour The Beyoncé Experience (2007). A live album titled The Beyoncé Experience Live was also released.

Between March 2002 and March 2003, Beyoncé had productive studio sessions while recording her debut solo studio album Dangerously in Love, recording up to 45 songs. After the release of Dangerously in Love in June 2003, Beyoncé had planned to produce a follow-up album using several of the leftover tracks. However, on January 7, 2004, a spokesperson for her record label Columbia Records announced that Beyoncé had put her plans on hold in order to concentrate on the recording of Destiny Fulfilled, the final studio album by Destiny's Child, and to sing "The Star-Spangled Banner" at the Super Bowl XXXVIII in Houston, Texas, which was a childhood dream of hers. Furthermore, she starred as Xania in the 2006 comedy-mystery film The Pink Panther, which was filmed in 2004. She also spent the following two years promoting Destiny Fulfilled and Destiny's Child's first greatest hits album #1's (2005), embarking on their final world tour Destiny Fulfilled... and Lovin' It; the group would disband in 2006.

Beyoncé originally recorded "Check on It" for The Pink Panther soundtrack; although its soundtrack inclusion was cancelled, it was released as the second single from #1's in December 2005 and became Beyoncé's third solo US Billboard Hot 100 number-one single, later appearing as a bonus track on the international editions of B'Day. In late 2005, Beyoncé decided to postpone the recording of her second studio album because she had landed the lead role in Dreamgirls, a film adaptation of the Tony Award-winning Broadway musical of the same name (1981). As she wanted to focus on one project at a time, Beyoncé decided to wait until the film was completed before returning to the recording studio. Beyoncé later told Billboard: "I'm not going to write for the album until I finish doing the movie."

While having a month-long vacation after filming Dreamgirls, Beyoncé went to the studio to start working on B'Day. She said: "[When filming ended] I had so many things bottled up, so many emotions, so many ideas", prompting her to begin working without telling her father and then-manager Mathew Knowles. Beyoncé kept the recording somewhat quiet, telling only her artists and repertoire executive Max Gousse, and the team of producers they contacted to collaborate with on the album. She began working with songwriters and producers Rich Harrison, Rodney Jerkins, Sean Garrett, Cameron Wallace, the Neptunes, Norwegian production duo Stargate, and American hip hop producer and rapper Swizz Beatz. Two female songwriters, who helped structure the album, were also a part of the team–Beyoncé's cousin Angela Beyincé, who had previously contributed to Dangerously in Love, and up-and-coming songwriter Makeba Riddick, who made her way onto the team after writing "Déjà Vu", the lead single off the album.

Beyoncé rented the Sony Music Studios in New York City, and was influenced by her now-husband Jay-Z's method of collaborating with multiple record producers; she used four recording studios simultaneously. She booked Harrison, Jerkins and Garrett, each with a room to work in. During the sessions, Beyoncé would move from studio to studio to check her producers' progress, later claiming this fostered "healthy competition" among producers. When Beyoncé conceived a potential song, she would tell the group who would deliberate, and after three hours the song would be created. While Beyoncé and the team brainstormed the lyrics, other collaborators such as the Neptunes, Jerkins and Swizz Beatz would simultaneously produce the tracks. They would sometimes spend up to 14 hours a day in the studios during the recording process. Beyoncé arranged, co-wrote and co-produced all of the songs on the album. Riddick, in an interview with MTV News, recounted her experience in the production: