The evolution of musical forms such as the sonata and symphony significantly influenced classical music during the Classical and Romantic periods. In the Classical era (1750-1820), composers like Haydn, Mozart, and early Beethoven formalized these structures, focusing on clarity, balance, and form. The sonata form, a three-part structure (exposition, development, recapitulation), became foundational for instrumental works, enabling thematic development essential for embodying the era’s ideals of order and reason.

The symphony, which evolved from the Italian overture and orchestral suite, applied these principles to larger ensembles. Haydn’s 104 symphonies established the four-movement structure, enhancing orchestral capabilities. Mozart’s symphonies introduced lyrical elegance and complexity, while Beethoven’s groundbreaking Ninth Symphony integrated emotional depth and innovative motifs, bridging Classical and Romantic styles.

In the Romantic period (1820-1900), composers like Schubert, Schumann, Brahms, and late Beethoven further developed these forms by infusing personal expression, expanding harmonic language, and extending formal boundaries. Symphonies became longer and more complex, exploring profound themes with larger orchestras. This transition marked a shift from the structured elegance of the Classical period to the emotional intensity and individualism characteristic of the Romantic era, significantly advancing classical music.