1. Exposition: The sonata-allegro form typically starts with an exposition section. This section introduces the main themes, keys, and melodic material used in the movement. It often consists of two contrasting themes or musical ideas.
2. Development: After the exposition, the development section follows. This section explores and develops the themes from the exposition, often presenting them in different keys, harmonies, and variations.
3. Recapitulation: Following the development is the recapitulation section. Here, the themes from the exposition are presented again, typically in the original key, providing a sense of resolution and balance to the movement.
4. Coda: Sometimes, a coda is added at the end of the recapitulation to further conclude or elaborate on the piece, but this is optional and not always present.
Therefore, the sonata-allegro form represents a common and pivotal genre of the Classical Period, frequently encountered in symphonies, sonatas, and other Classical era compositions.