Piano Rolls are a form of punched media aimed at the specific application of reproducing music through specifying a sequence of piano keys to be pressed. A player piano reads the punched holes in the roll as it moves through the reader portion of the device, and this triggers the pressing of the appropriate keys under automated control. In the late 19th and early 20th centuries, player pianos competed with another newly-created medium, the phonograph, as the medium for the public to purchase and play "canned" music instead of doing live musical performances by hand. Famous musician John Philip Sousa famously denounced all of them as "infernal machines" that were killing real music.
Some piano roll formats include velocity information, and in the 1920s famous pianists such as Rachmaninoff and Gershwin made piano roll recordings. They lack many of the subtleties of a live performance, but they're free of the noise and distortion that characterized acoustic recordings of that period, and some of these recordings have been re-released on CD. Most piano rolls, though, include only attack and release information, producing a mechanical sound.
Paper rolls, generally 11 1/4 inch wide. Well preserved ends should angle the paper toward the center where it meets in a tab that will have a hole to connect to the take up roller.
65 note scale introduced in 1896 with 6 holes to the inch on center. Rolls had pins on end.
88 note scale introduced in 1900 with 9 holes to the inch on center.
72 note scale introduced in 1902.
In 1909 United States standardized on the 88 note scale.