The Big Bang Theory is an American sitcom created by Chuck Lorre and Bill Prady. Who are also both executive producers on the show along with Steven Molaro. All three also serve as head writers. The show is centered on five characters: roommates Leonard Hofstadter and Sheldon Cooper, Penny, a waitress and aspiring actress who lives across the hall. Leonard and Sheldon's equally geeky and socially awkward friends aerospace engineer Howard Wolowitz and astrophysicist Raj Koothrappali. The geekiness and intellect of the four guys is contrasted for comic effect with Penny's social skills and common sense.