Thousands of finely engineered and carefully crafted moving parts make up a piano action. They are responsible for the way in which a piano’s hammers to strike the strings in response to the hand of the pianist. Over time and due to various conditions, responsiveness can change and degrade, with one or more keys on the piano growing out of sync with the others. Regulation is the mechanical adjustment of the many parts and subsystems in a piano to restore optimal touch and control for a pianist.