Exposition

The exposition is the opening section of a sonata-form movement. Its function is to present (‘expose’) the principal thematic material — typically a first theme group in the home key, a transitional passage modulating to a related key (usually the dominant or relative major), and a second theme group in the new key. A closing section (codetta) often rounds off the exposition.

The exposition is the foundation of sonata form. Everything that follows — the development, the recapitulation — refers back to the thematic material introduced here. Composers often mark the exposition with a repeat sign, asking that it be played twice; the second hearing reinforces the themes in the listener’s memory before the development begins.

The exposition is contrasted with the development (which manipulates and explores the exposed themes) and the recapitulation (which restates the themes in the home key). Together these three sections form the standard sonata-form architecture.

Latin expositio (‘setting forth’), from exponere (‘to set forth, expose’).

Play themes with characteristic clarity. The exposition introduces material the audience will hear again — establish each theme’s identity firmly. Mark the modulation between theme groups; the key change is structurally significant.