What is a piano?

Piano,a musical instrument with keyboard, a large musical instrument consisting of a keyboard fixed to a wooden case containing metal wires stretched across a frame. It is played by pressing the keys, each of which is attached to a small hammer that strikes one or more of the wires to sound a note.

Picture below show some major parts of a piano.

A piano consists of few major parts, there are piano keys, hammers, pedals, strings, dampers and soundboard. I will give you all some brief introduction about these few major parts of a piano.

1. Piano keys

The piano parts most of us recognize in a piano are the keys. Most modern-day pianos have 88 keys. Some older instruments have 85 keys.
Only a small part of a piano key is visible from the outside and it extends deep inside the instrument so that the piano action can be initiated. On vertical pianos the smaller the piano generally the shorter the key, which can lead to leverage problems. In order to obtain the depth to which a key must be pressed down this leverage problem at the key can translate into problems with the geometry of the action. Better pianos have extra piano parts in the form of key weights made of lead inserted into the keys which influence how well a piano action works. Better pianos will have each key individually weighted so that the touch across the keyboard is completely consistent from note to note.

2. Hammers

The piano is a percussion instrument. While we think of drums or a marimba being struck by hammers it is generally thought that the piano is a string instrument because of the strings. However, these strings are hit by hammers and not bowed to produce the sound.Initially pianos used leather covered wooden hammers; presently, felt hammers are used and a hammer consists of a wooden molding covered with one or two and even three layers of compressed wool felt which vary in density.
The hardness of piano hammers affects the sound quality or tone. While hard hammers can produce sharp and clear tones, some would consider them perhaps hard and noisy. Softer hammers can produce more mellow or even dull tone. This is because hard hammers excite high frequency modes of a piano string’s vibration whereas the soft hammers are unable to do so.

3. Pedals

The typical piano these days has 3 pedals – the Right Pedal, Middle Pedal and the Left Pedal which are part of another system of piano parts known as the trapwork.
Right Pedal – Also known as the Damper Pedal or Sustain Pedal is the most frequently used of the three pedals - many piano players never using the other two. Depressing the right pedal lifts the dampers from the piano strings; as a result, all the strings continue to vibrate irrespective of the note being played. When the pedal is returned to rest, the dampers do likewise.
Middle Pedal – Also known as the Sostenuto pedal, this pedal selectively sustains notes on a grand piano while all other sounds are stopped. In the vertical, this pedal tends to be a mute feature so that the piano is played extremely soft. This is so you don't disturb your neighbours - or perhaps your family.
Some uprights and most baby grands make use of a bass sustain in place of the Sostenuto pedal. While these uses for the middle pedal are fairly common now, manufacturers are known to have made rather innovative uses of the middle pedal such as a bar that would come down in front of the hammers in uprights. This bar would have pieces of leather in front of each hammer with a piece of metal inside. The sound produced would be a rinky tinky sound that was available in many pianos in the first years of the 20th century.
Left Pedal – Invented by Cristofori, the inventor of the piano. The left pedal shifts the keyboard so that all of the piano parts of the action, including the hammers, are able to strike only one or two strings for each note. Originally, the pedal was intended to strike only one string and was named the 'una corda’ pedal, which is Italian for ‘one string’.

4. Strings

There are approximately 250 very strong steel wire 'strings' in a piano and it is the vibration of these steel wires that generates the sound. The thickness of the strings changes from the bottom to the top of the piano, but for each note (bass notes have 1 or 2 strings, the tenor two or 3 strings, and the treble 3 strings) they must be very consistent in thickness. Variations greater than 0.0003 inches (0.0076 mm) will give tonal distortion as well as drive your piano technician nuts.
Piano strings are made of high quality steel so they can endure years of high tension, blows and bending. The bass strings have their steel core wrapped in copper in order to lower the pitch.

5. Damper

The dampers are the piano’s mechanism for stopping piano strings from vibrating. A damper is actually a small felted block that rests on a piano string in the grand or is held against the string in the upright by a spring to stop its vibration as soon as the key is released by the pianist.

6. Soundboard

The soundboard of a piano amplifies the vibrations of the piano strings, transmitting it to the air. Most soundboards are made of spruce which is straight grained and light providing good vibrational quality. There are some inexpensive pianos that the soundboards are made of mahogany.
The big sheet of wood you see behind the upright piano is the soundboard. On the grand, the soundboard can be seen underneath the strings and harp or cast iron plate.
The thrill given by the deftness of the pianist heartily thank the many minds and hearts behind the mechanical marvel that is a piano. Unless the thousands of piano parts work together well, the music quality will suffer.

A video that introduce some parts of a piano.