A background actor, also known as an EXTRA, is someone who appears in a film or television show without having any lines of dialogue. They are usually used to fill out a scene and provide atmosphere. Background actors are often hired to play specific roles such as a police officer, a waiter, or a pedestrian. They may also be asked to perform certain actions such as walking, running, or dancing. Background actors are essential to the production of a film or television show and can help create a realistic and believable atmosphere.