Piano
Stringed keyboard musical instrument, derived from the harpsichord and the clavichord. Also called the pianoforte, it differs from its predecessors principally in its hammer-and-lever action, which allows the player to modify the intensity of sound depending on the force of the player's touch. The earliest known model (1709) was built by Italian harpsichord maker Bartolomeo Cristofori.

How a piano operates
Essentially, when a piano key is pressed down, its tail pivots upward and lifts a lever that throws a hammer against the strings for that key's note. At the same time a damper is raised from these strings, allowing them to vibrate more freely. When the key is even partially released, the damper falls back onto the strings and silences the note. When the key is fully released, all parts of the mechanism return to their original positions because of gravity. Unlike grand pianos, upright pianos cannot rely on gravity to cause everything to return to place; therefore they include various springs and small strips of cloth to pull some of the action parts back into place.

Modern Structure of piano
The modern piano has six major parts:

  1. The frame is usually made of iron. At the rear end is attached the string plate, into which the strings are fastened. In the front is the wrest plank, into which the tuning pins are set. The strings are wound around the tuning pins, which are turned to regulate the strings' tension.
  2. The soundboard, a thin piece of fine-grained spruce placed under the strings, reinforces the tone by means of sympathetic vibration.
  3. The strings, made of steel wire, increase in length and thickness from the treble to the bass.
  4. The action is the entire mechanism required for propelling the hammers against the strings. Its most visible part is a row of keys, called a keyboard, manipulated by the fingers.
  5. The pedals are levers pressed down by the feet. One pedal, called the damper, or loud pedal, raises all the dampers so that all the strings struck continue to vibrate even after the keys are released. The soft pedal either throws all the hammers nearer to the strings so that the striking distance is diminished, or shifts the hammers a little to one side so that only a single string instead of the two or three is struck. Some pianos have a third, or sustaining, pedal that keeps raised only those dampers already raised by the keys at the moment this pedal is applied.
  6. According to the shape of its case, a piano is classified as square, grand, or upright. The square form (actually rectangular) is no longer built. Grand pianos range from the full concert grand, 2.69 m (8 ft 10 in) long, to the parlor or baby grand, less than 1.8 m (less than 6 ft) long. In the upright piano the strings run vertically or diagonally from the top to the bottom of the instrument.