How did Antonio Vivaldi use ritornello form in his concerti?

Antonio Vivaldi was the first composer to employ the ritornello form regularly in his concerti, a structural innovation that helped define the late Baroque style.1

In this form, Vivaldi utilized a recurring musical refrain—the ritornello—that alternates with contrasting episodic passages featuring a solo instrument. By creating bold juxtapositions between these refrains and the solo sections, Vivaldi opened new possibilities for virtuosic display by the soloist.1

While the ritornello provided a structural framework, the fast movements of his concerti are particularly noted for their rhythmic drive and the boldness of their themes. This approach to form became a model for many other composers of the era, including Johann Sebastian Bach, who transcribed several of Vivaldi's works.1