A piano sonata is a sonata written for unaccompanied piano. Piano sonatas are usually written in three or four movements, although piano sonatas have been written with one movement (Scarlatti, Scriabin), two movements (Beethoven), five (Brahms' Third Piano Sonata) or even more movements. The first movement is usually composed in sonata form.

Piano sonatas in the Classical era :

Although various composers in the 17th century had written Piano pieces which they entitled "Sonata", it was only in the classical era, when the piano displaced the earlier harpsichord and sonata form rose to prominence as a principle of musical composition, that the term "piano sonata" acquired a definite meaning and a characteristic form.

All the well-known Classical era composers, especially Joseph Haydn, Muzio Clementi, Wolfgang Amadeus Mozart, and Ludwig van Beethoven, wrote many piano sonatas. Muzio Clementi wrote more than 110 piano sonatas. He is well-known as the "The Father of the Pianoforte". Clementi's Op.2 is the first real piano sonata. The much younger Franz Schubert also wrote many. The 32 sonatas of Beethoven, including the well-known Pathétique Sonata and the Moonlight Sonata, are often considered the pinnacle of piano sonata composition.