The invention of the piano by Bartolomeo Cristofori hinged on one brilliant mechanical part: the 'escapement.' In a harpsichord, the string is plucked, but in a piano, a hammer must strike the string and immediately bounce back (escape) so the string can continue to vibrate. Without the escapement, the hammer would stay pressed against the string, 'muting' the sound instantly. The escapement allows the hammer to fall back even if the player is still holding the key down, enabling the piano’s characteristic sustain and dynamic range.