An exposition in music theory is an essential element of sonata form, which is commonly used in classical music. It refers to the first section of a piece of music that introduces the main themes or musical ideas that will be developed throughout the rest of the composition.

Structure of an Exposition

An exposition typically consists of two or more contrasting themes, which are presented in different keys and are often separated by a bridge or transition. The first theme, also known as the primary theme or subject, is usually presented in the tonic key (the main key of the piece) and establishes the tonality and mood of the composition.

The second theme, also known as the secondary theme or subordinate subject, contrasts with the first theme and is usually presented in a different key. This helps to create tension and interest within the music. The exposition may also include a closing section that brings together all the thematic material introduced earlier.

Importance of Exposition

The exposition plays a crucial role in creating structure and coherence within a piece of music. By presenting contrasting themes and developing them throughout subsequent sections, composers can create a sense of narrative and progression within their compositions.

The exposition also provides listeners with an initial impression of what they can expect from the rest of the piece. It sets up expectations for musical development and variation throughout subsequent sections such as development and recapitulation.

Exposition vs Development vs Recapitulation

After an exposition comes development where previously introduced themes are developed further through various techniques such as modulation, inversion, or fragmentation. Recapitulation is then used to bring back all previously introduced themes but this time they are played entirely in tonic key.


In conclusion, an exposition is a vital element in classical music composition that sets up expectations for listeners while providing structure and coherence throughout subsequent sections. Understanding its role in music theory can help us appreciate the complexity and beauty of classical music.