Definition of "Exposition" :

noun: (music) the section of a movement (especially in sonata form) where the major musical themes first occur

noun: an account that sets forth the meaning or intent of a writing or discourse

"We would have understood the play better if there had been some initial exposition of the background."

noun: a systematic interpretation or explanation (usually written) of a specific topic

noun: a collection of things (goods or works of art etc.) for public display