Photo Flash: Usher, Diddy, will.i.am & More On AMERICAN IDOL!

On Wednesday, March 31, AMERICAN IDOL welcomed guest appearances by superstars Usher, Diddy, wil.i.am, and IDOL seaseon 2 winner Reuben Studdard. Check out the pictures below - including photos from Tuesday's performance show.

'American Idol' is a reality competition to find new solo musical talent, created by Simon Fuller. It debuted June 11, 2002 on the Fox network and has since become one of the most popular shows on American television. It is currently the #1 TV show in the Nielsen Ratings and is one of only three that have been #1 for five consecutive seasons.

The cast of "Idol" includes judges Simon Cowell, Randy Jackson, Kara DioGuardi, and Ellen Degeneres, and host Ryan Seacrest.

The program aims to discover the best singer in the country through a series of nation-wide auditions, and subsequent viewer voting. Through telephone voting, America has chosen past winners Kelly Clarkson, Ruben Studdard, Fantasia Barrino, Carrie Underwood, Taylor Hicks, Jordin Sparks, David Cook, and Kris Allen.

Several "Idol" contestants have been seen on the Broadway stage, including Barrino (The Color Purple), Hicks (Grease), Clay Aiken (Spamalot), Diana DeGarmo(Hairspray), Josh Strickland (Tarzan), Tamyra Gray (Rent, Bombay Dreams), and Constantine Maroulis (The Wedding Singer, Rock of Ages).

Photo Credit: Michael Becker / FOX