B'Day is the second solo studio album by American R&B singer Beyoncé. Columbia Records, in collaboration with Music World Music and Sony Urban Music, released it worldwide on September 4, 2006 to coincide with Beyoncé's twenty-fifth birthday (see 2006 in music).

The album was originally planned for a 2004 release as a follow-up to her debut album Dangerously in Love. However, the project was put on hiatus due to the recording of Destiny's Child's final album Destiny Fulfilled and her starring role in the 2006 movie Dreamgirls. While having a vacation after filming Dreamgirls, Beyoncé began contacting various producers, and completed B'Day in just three weeks.

Most of the lyrical content of the album was inspired by Beyoncé's role in the film. The musical style of the songs range from '70s to '80s funk and balladry to urban contemporary elements like hip hop and R&B. Live instrumentation was employed on most tracks as part of Beyoncé's vision of creating a record using only live instruments. The album has vocal appearances by Jay-Z, Shakira, and others.

B'Day was commercially successful, topping the U.S. Billboard 200 chart on its debut. It sold 541,000 units within a week of release, beating its predecessor, Dangerously in Love. The album yielded six singles, and was successful in other markets, entering the top ten of many charts worldwide. B'Day was re-released as an expanded double-disc deluxe edition on April 3, 2007 when Beyoncé embarked on The Beyoncé Experience world concert tour. A DVD counterpart was also released, featuring ten music videos from the album's songs. B'Day was certified multi-platinum and received several awards, yet many critics of the genre were divided in their reviews. The album has sold nearly six million copies worldwide.