THE BIG BANG THEORY is a TV comedy about a group of friends in Pasadena, California. Leonard and Sheldon are scientists. They work together and they share a flat too. Two other friends from work, Howard and Raj, often visit them. Penny lives opposite. She works in a restaurant. She likes Leonard and Sheldon, but they are very different from her. A lot of the humour comes from this contrast. It's a simple idea for a show, but millions of people watch and enjoy it every week. Clearly, people love shows about friends!