Sonata-allegro form is a musical structure that is used in the first movement of many classical symphonies, sonatas, and concertos. It consists of three main sections: the exposition, the development, and the recapitulation.
* The exposition introduces the main themes of the movement.
* The development explores and develops these themes in a variety of ways.
* The recapitulation restates the main themes in their original keys and order.
Sonata-allegro form is a complex and versatile musical structure that allows composers to create a wide variety of musical effects. It is one of the most important innovations of the classical era and has been used by composers ever since.