MacGuffin :)

MacGuffin

A MacGuffin is an object or device used in films, that serves as a trigger for the plot. A MacGuffin doesn't affect the audience, but it does affect the characters. The audience may care for the MacGuffin  at first, and they may wonder what's it's for, and why it is obsessed over by the characters, but the audience soon forget about it. To the audience, MacGuffins are seen as meaningless and easily replaceable, but to the characters it is of vital importance, as it drives the story, even ifit was an unimportant object or just mentioned and never seen.