Every episode of DIARY includes the following catchphrase: "You think you know, but you have no idea. This is the diary of (insert celebrity name here)." With this set-up, the series proclaims that there is so much more work to celebrity life than the public realizes. Diary then proceeds to take viewers behind the scenes of a day in the life of a celebrity promoting their latest project (past subjects have included Ludacris, Hilary Duff, Britney Spears, Kanye West, Angelina Jolie, Bono, the cast of One Tree Hill, Chris Rock, Good Charlotte, and Shakira). Typical activities include radio interviews, photo shoots, re-recording movie dialogue, listening to the latest version of a new single, or getting ready to hit the red carpet. Scenes of work and play are interspersed with shots of the star speaking directly into the camera, which generally connects back to the celeb's latest work -- who they worked with, how much fun they had, how much they respect a particular producer, and how enthusiastic they are about their latest accomplishment.