If you're considering buying a piano, then you should know more about the parts of the piano to help you make an informed and wise decision.  Following are some important facts about the parts of a piano that will help you in your decision.

The Back
When you begin your inspection of a vertical piano, look at the back.There will be five or six vertical posts that serve as stays against the frame, giving added strength to resist the tremendous pull of the strings inside. The posts should be heavy and strong enough to provide adequate support in proportion to the rest of the piano. 

Soundboard
Next, ask about the soundboard, a wooden board at the back (or inside of a grand) that translates the vibrations of the strings into the "tone" of the piano. The soundboard is one of the vital parts of the piano, and is is made of spruce in many top-quality instruments.The fine, straight grain in spruce is ideal for conducting sound. The ribs on the back of the soundboard should run from one edge of the soundboard to the other for support. 

Plate & Bridges
The plate is an irregularly-shaped piece of cast iron bolted to the back of the frame. It holds one end of the piano strings, and anchors most of the 20 tons of pull exerted by the taut strings. The treble and bass bridges are another of the piano's vital organs. These long pieces of hard maple are attached to the soundboard, transferring the vibrations of the string to it. 

Strung Back
When piano dealers refer to the "strung back," they mean the parts just discussed plus the strings, which are made of high-grade steel drawn to exact sizes. The bass strings are wound with wire to add weight and reduce the frequency at which the string vibrates. This allows the use of relatively shorter string to produce deeper notes. At the top of the plate, the strings are wound through and around tuning pins. These are set into the pin block, constructed of layers of carefully seasoned hard wood which grips the pins in place for tuning stability. 

Action
The working section of the piano is called the action. There are about 7,500 parts here, all playing a role in sending the hammers against the strings when keys are struck. Grand pianos all have horizontal action, and upright pianos have vertical action. There are two kinds of vertical action--"direct-blow," which pushes the mechanism that controls the hammer, found in taller pianos; and "indirect-blow" or "drop" action, which pulls the mechanism in lower silhouette instruments. 

Hammers
Piano hammers are formed of one or two layers of felt forged onto the wooden hammer molding under tremendous pressure. If a dealer talks to you about a 9-pound hammer as opposed to a 12-pound hammer, he means the weight of the sheets of felt that were used to make the hammers. 

Tuning & Regulation
By the time you see the piano in the showroom, it has been tuned at the factory several times, starting with the "chip" or rough tuning before the mechanism is even locked into the cabinet. The last fine adjustment, called "voicing," includes the regulation of the hammer felts for individual notes. 

Keys
Now, you can take your head out of the inside of the piano, and consider the externals again. 
The piano keys rest in the key bed, a perfectly flat well in the front of the cabinet that keeps the keys level. Each key is balanced by a center pin, and "bushed" with fine wool for silence and proper clearance. The "ivories" are not ivory anymore, but a fine molded plastic that won't crack or turn yellow. The black keys are made of a similar material. 

Pedals
Most pianos have three pedals, but most pianists need only two. The sustaining, or damper pedal on the right lifts the dampers (which in a resting position prevent the strings from vibrating) away from the strings so that the tone is sustained after the keys are released. The pedal on the left, called una corda, mutes the tone by shortening the distance the hammers travel or by shifting the action slightly so fewer strings are hit. Many pianos have a third pedal for sustaining bass tones only, On most grand pianos ansd some uprights, the third pedal is a sostenuto, which sustains selected tones at the pianist's discretion. 

Cabinet
Finally, there's the cabinet, that handsome piece of furniture that will take a prominent place in your decor. Modern cabinets are made of core stock overlaid with thin veneers of fine furniture wood. Many grains and finishes are available and modern finishing techniques assure excellent appearance and easy care for years.