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. The series' tenth season premiered on September 19, 2016. 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 is set to premiere on September 25, 2017.
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.
Over time, supporting characters have been promoted to starring roles: Leslie Winkle, a physicist who dated Leonard and Howard; neuroscientist Amy Farrah Fowler, who joins the group after being matched to Sheldon on a dating website (and later becomes Sheldon's girlfriend); Bernadette Rostenkowski, Howard's wife (previously his girlfriend), a microbiologist and former part-time waitress alongside Penny; Stuart Bloom, the cash-strapped owner of the comic book store the characters often visit; and Emily Sweeney, a dermatologist who dated Raj.