A piano roll is a music storage medium used primarily in player pianos and some automatic musical instruments. It consists of a long strip of paper with holes punched in it, where each hole corresponds to a specific note. When the roll is fed through the instrument, the holes trigger hammers that strike the piano keys, producing music. In modern music production, a digital version of the piano roll is often used in software like MIDI sequencers. This digital piano roll visually represents notes on a grid, allowing musicians to compose and edit music easily by placing and adjusting notes on the screen.