A piano roll is the music storage medium used to operate the player piano, pianola or a reproducing piano.

The piano roll was the first medium which could be produced and copied industrially and made it possible to provide the customer fast and easy with actual music.

A piano roll is a roll of paper with perforations (holes) punched in it. The position and length of the perforation determines the note played on the piano. The piano roll moves over a device known as the 'tracker bar', which first had 58 holes, was expanded to 65 and then was upgraded to 88 holes (generally, one for each piano key). When a perforation passes over the hole, the note sounds.

Piano rolls have been in continuous mass production since around 1896. Though they are still being made today, MIDI files represent a modern way in which musical performance data can be stored. MIDI files accomplish digitally and electronically what piano rolls do mechanically. Software for editing a performance stored as MIDI data often has a feature to show the music in a piano roll representation.

The first paper rolls were used by Welte & Sons in their Orchestrions since 1883. US-Patent 287.599, Emil Welte, New York, 30. October 1883 http://www.welte-mignon.de/pdf/Orchestrion/USOrchestrion/US0287599.pdf After hundreds of companies of this booming business produced piano rolls different in size and perforation, in 1909 the American producers of piano rolls and mechanical pianos as well agreed to a standard in the Buffalo Convention.