The Piano Sonata No. 11 in A major, K. 331 (300i), by Wolfgang Amadeus Mozart is a piano sonata in three movements. It is uncertain where and when Mozart composed the sonata; however, Vienna or Salzburg around 1783 is currently thought to be most likely (Paris and dates as far back as 1778 have also been suggested). The sonata was published by Artaria in 1784, alongside Nos. 10 and 12 (K. 330 and K. 332).
All of the movements are in the key of A major or A minor; therefore, the work is homotonal. A typical performance of this entire sonata takes about 20 minutes.
The last movement, "Alla Turca", popularly known as the "Turkish March", is often heard on its own and is one of Mozart's best-known piano pieces; it was Mozart himself who titled the rondo "Alla Turca". It imitates the sound of Turkish Janissary bands, the music of which was much in vogue at that time. Various other works of the time imitate this Turkish style, including Mozart's own opera Die Entführung aus dem Serail. In Mozart's time, the last movement was sometimes performed on pianos built with a "Turkish stop", allowing it to be embellished with extra percussion effects.