Piano
A piano has a keyboard with white keys and black keys. When a key is pressed down, the damper comes off the string and a hammer hits the string. It hits it very quickly and bounces off so that the string is free to vibrate and make a sound.  Each key is a level that makes a hammer inside the piano hit a string inside, producing a sound. Each string has a different length and so produces-a different note. When the player takes their finger off the key the damper falls back onto the string and the sound stops.  The strings are stretched very tightly across the frame, passing over a bridge on the way.  The bridge touches the soundboard.  This means that the vibrations are sent to the soundboard.  The soundboard is a very important part of the piano.  If it is damaged the piano will not make a sound.