Piano Sonata No. 23, also known as the "Appassionata," is a piano sonata composed by Ludwig van Beethoven between 1804 and 1806. It is one of his most celebrated works, characterized by its emotional depth and technical challenges. The sonata is structured in three movements: Allegro, Andante con moto, and Allegro ma non troppo. The first movement is intense and dramatic, while the second offers a contrasting lyrical quality. The final movement returns to the passionate energy of the first, showcasing Beethoven's innovative use of harmony and rhythm. This sonata is a significant piece in the classical piano repertoire.