Season 1
The first season of the American sitcom The Big Bang Theory was originally aired on CBS from September 24, 2007, to May 19, 2008, over 17 episodes. An unaired pilot also exists. The Season 1 DVD came without a gag reel and is, so far, the only Big Bang Theory DVD set not to have one. The reissued Blu-ray, was released July 10, 2012, and includes a gag reel that is exclusive to the set. The episodes on Blu-ray are all in remastered surround sound, whereas the DVD version had stereo.
Season 2
The second season of the American sitcom The Big Bang Theory was originally aired on CBS from September 22, 2008 to May 11, 2009 over 23 episodes. The Complete Season DVD was released September 15, 2009, and a Blu-ray version was reissued on July 10, 2012 with remastered surround sound audio, whereas the DVD version only had stereo. Season two starts immediately after the end of season one with and Leonard and Penny's date.
Season 3
The third season of the American sitcom The Big Bang Theory was originally aired on CBS from September 21, 2009 to May 24, 2010 with 23 episodes. It has received higher ratings than the previous two seasons with over 15 million viewers. The Complete Third Season DVD erroneously credits Mark Cendrowski for directing nearly the entire season. Season three starts three months after the end of season two when the guys left for the North Pole.
Season 4
American sitcom The Big Bang Theory, which began airing on CBS on September 23, 2010. During the season, actress Kaley Cuoco was absent from some episodes after she broke her leg in a horse-riding accident. When she returned to the series she was shown working as a bartender instead of waitressing at her usual workplace, The Cheesecake Factory, to hide her injury. In January 2011, The Big Bang Theory was renewed for an additional three years; extending it through the 2013/14 season, for a fifth, sixth, and seventh season. Season four starts four months after the end of season three and Sheldon Cooper's first date with Amy Farrah Fowler.
Season 5
The fifth season of the American sitcom The Big Bang Theory was originally aired on CBS from September 22, 2011 to May 10, 2012 over 24 episodes.