Exposition is a necessary tool for the screenwriter and often one that is essential to understanding plot, character, setting, and/or theme because it provides an explanation of necessary background information to the audience. Every film has it, but not every film does it well.
When the presentation of the information comes out as a forced monologue, it is often referred to as an "info dump" or "idiot lecture." Good exposition, however, never simply "dumps" information in our lap. The skilled screenwriter delivers it through conflict (an argument that starts about one thing escalates when past issues are brought up), through humor (a character teasing another will often illustrate by referring to events of the past), through a character whose occupation demands a delivery of information (professor, lawyer, judge, scientist, etc), or during intense action (a car chase, a shootout, or even just a jog through the park).
Since there are so many different purposes for exposition and it can be presented in so many different ways, we felt it was necessary to narrow the road and base our list on two very distinct rules: Rule #1 – Exposition that occurs in one singular scene & Rule: #2 – Exposition that delivers information ONLY on plot and/or the world of the story.