What are the three main parts of a sonata form?

Sonata form is a dramatic structure, consisting of three main parts: the Presentation, the Exposition and the Repertoire. The Presentation section contains the main and secondary sections in different keys, and successively states two or more themes of contrasting character, just as the first act of a play reveals the main characters. The Expanding Section uses various techniques to develop the themes in the Presenting Section in a varied manner. It shows their interactions and conflicts, just as the second act of a play actively unfolds the plot. The recapitulation section, on the other hand, recapitulates the themes in the presentation section at a new level of tonal unity, like the final act of a play, showing the basic unity and resolution of the conflicts. The first movement, written in sonata form, is best suited to express the intense activity and struggle of the people.