<Tr> <Th_colspan="2"> External links </Th> </Tr> <Tr> <Td_colspan="2"> Website </Td> </Tr> <P> The Big Bang Theory is an American television sitcom created by Chuck Lorre and Bill Prady, both of whom serve as executive producers on the series, along with Steven Molaro . All three also serve as head writers . The show premiered on CBS on September 24, 2007 . In March 2017, the series was renewed for two additional seasons, bringing its total to twelve, and running through the 2018--19 television season . The eleventh season premiered on September 25, 2017 . </P> <P> The show is primarily centered on five characters living in Pasadena, California: Leonard Hofstadter and Sheldon Cooper, both physicists at Caltech, who share an apartment; Penny, a waitress and aspiring actress who later becomes a pharmaceutical representative and who lives across the hall; and Leonard and Sheldon's similarly geeky and socially awkward friends and co-workers, aerospace engineer Howard Wolowitz and astrophysicist Raj Koothrappali . The geekiness and intellect of the four men are contrasted for comic effect with Penny's social skills and common sense . </P>

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