Definition:
Every story has a before. Exposition is the part of the film that communicates what came before: the setting, the characters' histories, the rules of the world, and the context that makes the present action legible. It is necessary information delivered as engagingly as possible, which is harder than it sounds.
What It Means in Movies:
Do it badly, and characters explain things to each other that they would both obviously already know, purely for the audience's benefit. That is the cardinal sin of expository writing. Do it well, and the audience absorbs the same information through action, environment, visual detail, and dialogue that feels natural rather than functional.
Why It Matters:
Without exposition, audiences are lost. With too much, they are bored. The screenwriter's task is threading that needle: delivering the necessary information without the audience noticing it is being delivered. The best exposition in cinema does not feel like exposition at all. It feels like a scene.
Example:
The opening crawl of every Star Wars film is pure exposition. It delivers the political and narrative context of the galaxy before a single character appears. It works because it commits fully to its own artifice. Rather than hiding the exposition, it presents it as a ceremony.