What+is+Sonata+Form+by+Campbell+Ross

Sonata from, also known as sonata-allegro form, is a form of music that has been commonly used since the classical period. It consists of three main structures, an exposition, a development and a recapitulation. The usual definition may also use an introduction and a coda.
 * What is Sonata Form? **

Sonata form focuses on the harmonic and thematic organisation of tonal materials. Since it's institution, the sonata form became the most frequent of works allowed the first movement entitled "sonata", as well as other long works of classical music such as symphony, trio, string quartet ect.