Summary: The talent show's fourth season opens with preliminary auditions taped in theaters across the country. Nick Cannon is the new host, replacing Jerry Springer. David Hasselhoff, Sharon Osbourne and Piers Morgan return as the judges.

Summary: The judges travel to Miami for the first time in AGT audition history, in hopes of finding the next million-dollar act.

Summary: The coast-to-coast auditions continue as the judges search for the next million-dollar act.

Summary: The judges continue their search for the next million dollar act.

Summary: The judges continue their coast-to-coast search for the next big thing.

Summary: The judges continue their coast-to-coast search for the next big thing.

Summary: Auditions are now being held in New York City. Will the judges like what they see?

Summary: Performance showcases are featured in the eighth audition installment.

Summary: Performance showcases are featured in the ninth audition installment.

Summary: Performance showcases are featured in the 10th and final audition installment.

Summary: In the first "Vegas Verdicts" edition, winning acts from the preliminary auditions advance to Las Vegas in the hope of securing a coveted position in the Top 40, with the judges debating their show-biz fate.

Summary: In the second "Vegas Verdicts" installment, the judges debate the fates of the hopeful contestants to determine the Top 40 acts.

Summary: Ten of the Top 40 acts showcase their talents in the first performance edition.

Summary: The first five winning acts are selected for the Top 20 in a results edition. Mariah Carey performs, as does ventriloquist and Season 2 winner Terry Fator.

Summary: Ten acts from the Top 40 take to the stage in the second performance installment.

Summary: Five winning acts are selected to the coveted Top 20 in a results edition. Electro hip-hop duo LMFAO and comic illusionists Penn and Teller perform.

Summary: The third performance episode showcases 10 acts from the Top 40.

Summary: Five acts win a slot in the sought-after Top 20 in a results show. Daughtry and Ashley Tisdale perform.

Summary: The Top 40 acts have been narrowed to 10 and are featured in the fourth performance show.

Summary: Five final acts win a position in the Top 20 in a results show.

Summary: The semifinals kick off with the first 10 acts from the Top 20 taking the stage.

Summary: Four acts are selected to advance to the finals in a results edition. David Hasselhoff performs, as do the Muppets' Kermit the Frog and Miss Piggy.

Summary: Ten semifinal acts from the Top 20 perform.

Summary: A results edition reveals five winning acts. Members of the stage show "Jersey Boys"---a musical depicting the life of the pop group Frankie Valli and the Four Seasons---perform a medley of tunes from the show.

Summary: The final performance episode features the 10 finalists in showcases.

Summary: The winning act is revealed in the Season 4 finale. The victor scores $1 million. Performers include "Britain's Got Talent" phenom Susan Boyle; pop songstress Shakira; English singer Leona Lewis; country's Rascal Flatts; and Cirque du Soleil.