The Probert Encyclopaedia of Music

SONATA

Sonata is an important form of musical composition comprising classically four movements. The modern form of sonata was fixed by Emanual Bach in the 18th century. The same general structure prevails in symphonies, instrumental trios, quartets, etc., and even in classical concertos. The
sonata form, distinctively, characterises the quick opening movement, which may have a short, slow introduction; the second, or slow, movement is either in the song or variation form; third comes the playful minuet or the more modern scherzo; then the quick finale in the rondo form. But both form and order are sometimes exceptional.
Research Sonata