sonateformens

Sonateformen, commonly written in English as the sonata form, is a musical structure widely used in the Classical period for the first movements of instrumental works such as symphonies, sonatas, and string quartets. In Scandinavian languages the term is sonateformen; in English the standard term is sonata form. It is also known as sonata-allegro form.

The basic outline consists of an exposition, a development, and a recapitulation. The exposition introduces two (or more) themes, typically in contrasting keys: the first in the tonic and the second in a related key. The exposition is often repeated. The development processes the themes, modulating through a range of keys and exploring different tonal areas. The recapitulation reasserts the original material, with both main themes returning in the home key; a concluding coda may follow to close the movement.

Historically, the form emerged in the early 18th century from adapted Baroque binary forms and was refined by Haydn, Mozart, and Beethoven. It became the dominant architecture of the first movements in the Classical era and has continued to influence composers beyond that period. In some contexts, composers used variations such as an introductory slow section, or a double exposition in concertos, where a separate orchestral and solo exposition present the themes in turn.

Key principles of the form include unity of motive, contrast in key and character between the main themes, and a clear tonal return in the recapitulation. While the structure is traditional, composers frequently alter or extend sections, leading to numerous formal variants within the broader concept of sonata form.