Pianos is short for pianofortes, so called because they are so versatile in terms of dynamic. There are six main mechanisms through which pianos work in traditional playing: the pedals, the metal frame, the soundboard and bridges, the action, the casing, and the strings. There are multiple strings for each pitch, three for the treble notes, and two for the tenor notes, and one for the bass notes.
The action includes the keys, the hammers, and the hammer mechanism. Striking a key, causes the hammer mechanism to move and strike the strings. The bridges pick up the vibration of the strings and carry it to the soundboard. The metal frame keeps the strings in tension, and the casing encloses it.
The three standard pedals have three different effects on the sound of pianos. The left pedal, sometimes called the soft pedal, works in one of several ways. It may, for example, either adjust the hammer to the side so that it strikes only two treble strings and one tenor string, which is one way of reducing the sound, or shift the hammer to be closer to the strings, so that the hammerstroke is shortened. The right pedal, sometimes called the loud pedal, undamps the strings, allowing them to vibrate unimpeded. The middle pedal also affects the dampers, raising them, but only those for the notes that are being played when the pedal is engaged.
When a performance calls for prepared piano, pianos work in a variety of different ways. Prepared pianos are altered in ways that take advantage of a variety of timbre possibilities not attainable in performance otherwise. Prepared pianos may have their strings plucked, scraped, or struck directly by the performer, with hands or an implement. Material, such as paper, may be inserted between or among strings, changing the effects.
Prepared pianos may be partially dismantled, changing the resonance space. Other instruments may be played so that their sound hits the piano strings, causing sympathetic vibrations. Or the casing or metal frame may be struck, creating various other sounds.