The sonata (from the Italian sonare 'to sound') is a work for solo piano, or a solo instrument accompanied by piano, in three or four movements.
Sonata form, sometimes known as first movement form, describes the structure of the first movement of many sonatas, symphonies, and often overtures. It falls into three sections: exposition, development, and recapitulation. The exposition introduces two contrasting themes in related keys. These are developed and heard again in the recapitulation, this time in the same key.