Exposition (music)

In musical form and analysis, exposition is the initial presentation of the thematic material of a musical composition, movement, or section. The use of the term generally implies that the material will be developed or varied.

The term is most widely used as an analytical convenience to denote a portion of a movement identified as an example of classical tonal sonata form. The exposition typically establishes the music's tonic key, and then modulates to, and ends in, the dominant. If the exposition starts in a minor key, it typically modulates to the relative major key, or less commonly, the minor dominant. There are many exceptions—for example the exposition of the first movement of Beethoven's Waldstein Sonata modulates from C major to the mediant E major. The exposition may include identifiable musical themes (whether melodic, rhythmic or chordal in character), and may develop them, but it is usually the key relationships and the sense of "arrival" at the dominant that is used by analysts in identifying the exposition. The exposition in classical symphonies is typically repeated, although there are many examples where the composer does not specify such a repeat.

If the movement starts with an introductory section, this introduction is not usually analysed as being part of the movement's exposition.

In many works of the Classical period and some of the Romantic era, the exposition is often bracketed by repeat signs, indicating that it is to be played twice. This is something which is not always done in concert from the 20th Century onwards.

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