Published by Litolff, No.1181, n.d. (ca.1860), Collection Litolff No.1065.1181. (Braunschweig)

The Prelude Op. 28, No. 15, by Frédéric Chopin, known as the "Raindrop" prelude, is one of the 24 Chopin preludes. Usually lasting between five and seven minutes, this is the longest of the preludes. The prelude is noted for its repeating A♭, which appears throughout the piece and sounds like raindrops to many listeners.
The above text from the Wikipedia article "Prelude, Op. 28, No. 15 (Chopin)" text is available under CC BY-SA 3.0.