Exposition is a literary tool that is used to give information to the audience through
dialogue, description,
flashback, or
narrative.
In
nonfiction, exposition is commonly found in essays, directions such as recipes and instructions, encyclopedias, and
biographies. Exposition in
nonfiction is usually achieved through description.
In
fiction, exposition can be given in multiple ways. Sometimes it's as simple as a character observing a headline on a newspaper and sometimes as complex as the narrator giving an overview of the full history of the fictional world.
Exposition is a two-edged sword. While it is extremely useful for establishing setting, plot, and characterization, too much exposition at once can bog down a story and slow the pace to a crawl. An exposition that is overly long or wordy is known as an Information Dump (or
Infodump for short) and is very difficult to do well.
See
Information Desk for where
characters learn things; may overlap with this, considerably.
Tropes