Eine kleine Nachtmusik (Serenade No. 13 for strings in G major), K. 525, is a 1787 composition for a chamber ensemble by Wolfgang Amadeus Mozart (1756–1791). The German title means "a little night music" and it is one of the most famous pieces of classical music.
The reasoning behind this piece is unknown. The extant piece contains four movements: Allegro, Romance, Menuetto, and Finale. However, another movement is now believed to be lost.