The piano has 88 notes whose thickness and length of strings vary in order to create the 88 different tones. If the first note of the piano (A1) had a string of the same thickness as the last (C88), the instrument should be over 7 meters in length!
There are over 12,000 parts in every piano; made of wood, leather, steel, wool, felt, etc. Most of them are located in the action and are moving parts.
The response of the human ear to sound is logarithmic. This explains why when two pianos play together, they sound just louder than one and not twice as loud. To double the sound of a piano eight pianos are needed!<
The inventor of the piano, Bartolomeo Cristofori was born in Padua in 1655 and died in Florence in 1731. He built 20 pianos but only three survive today and are exhibited in museums in New York, Leipzig and Rome.
The piano is perhaps the only instrument that is completely autonomous and does not need another to accompany it. Instead, the piano accompanies all other instruments including voice.
Italian composer Lodovigo Giustini was the first who composed music especially for the piano (1732). The work was 12 sonatas, under the title Sonati di cembalo di piano e forte.
The piano is mainly used solo (in recitals) or as a solo instrument in concerts with orchestra. However, many were the composers (especially in the 20th century) who used it as part of the orchestra or the percussion section (e.g. Bartok, Williams and Stravinsky). American composer John Cage was famous for his compositions of the "prepared piano" were he made use of various objects within the instrument to manipulate the sound and create a reaction (spoons, Ping-Pong balls, etc.)!
Even though the piano has over 230 strings (on average), it is considered to be a percussion instrument rather than stringed. This is because the sound is created by the hammers and not by plucking the strings. However, many classify the piano as a separate category by itself.