Sonata Allegro Form
... The symphony is regarded as the central form of composition, and went from a three-movement piece to a four-movement piece. The sonata-allegro form was used often beginning in the Classical Period. The sonata form sets the structure for a single movement and consists of three sections. It is also described as being in “ABA” form – from the exposition to the development to the recapitulation. ... The Classical symphony has four movements in it, each one having a specific form.