The fourth season of American talent show competition series America's Got Talent was broadcast on NBC from June 23 to September 16, 2009. Following the previous season, Jerry Springer left the show due to other commitments, and was replaced as host by Nick Cannon. A number of changes were also made to the program before filming commenced, which included replacing the "boot camp" stage with a round similar in format to that used by Britain's Got Talent, and changing the buzzer format to match that being used by the Got Talent franchise. In addition, the episodes for results in each live round of the competition were also modified. They were broadcast over a one-hour period, and would feature performances by guest stars.
