Why did the Italian overture influence the three-movement symphony?

The Italian overture, or sinfonia avanti l'opera, significantly influenced the development of the three-movement symphony by providing a structural model that composers adopted and expanded.12

Formalized in the late 17th century by composers such as Alessandro Scarlatti, the Italian overture was characterized by a three-section fast–slow–fast (allegro–adagio–allegro) format. This structure offered a clear, balanced framework that contrasted with the more complex, contrapuntal style of the French overture.32

As these three contrasting sections were expanded into relatively self-sufficient movements, they became the foundation for the three-movement symphonies that emerged in the 1740s. By providing this established template, the Italian overture helped transition the sinfonia from a functional orchestral introduction for operas and cantatas into an autonomous musical composition.12