exposition

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

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

(noun) an account that sets forth the meaning or intent of a writing or discourse. Example: "We would have understood the play better if there had been some initial exposition of the background."

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