What is a MacGuffin?

A MacGuffin is a device used in many films, mostly thrillers, that acts as a goal or an objective that either the protagonist or the antagonist wishes to reach or achieve. This is what usually kick-starts the film as the pro/antagonist is desperate to pursue this motivator. The MacGuffin is a large part of a film however it is usually not the main focus of the film. It is usually what starts off the film and for the rest of film acts as a background element that is always there until the very end when the protagonist or antagonist reaches their goal. Some good examples of a MacGuffin in films we have previously studied are: The money that has been stolen in the film 'Psycho' and the antagonists smuggling microfilm in 'North by Northwest'.