According to the research, 86% of all professional musicians complain of some playing related problems and countless piano students and professionals suffer from many of the following symptoms:
 * Tension

* Pain​
* RSI

* Ganglia

* Carpal tunnel syndrome

* Technical Limitations

* Musical limitations

https://youtu.be/lGltEyx1Yb8

Pianos can have over 12,000 individual parts, supporting six functional features: keyboard, hammers, dampers, bridge, soundboard, and strings. Many parts of a piano are made of materials selected for strength and longevity.

When you press a key on the piano it causes a small hammer inside the piano to hit a string or strings. Each key is connected to its own hammer or hammers which hit a specific string or number of strings. When the hammer hits a string, it vibrates and makes a sound that is tuned to a specific note.

The piano was invented by Bartolomeo Cristofori (1655-1731) of Italy.  Cristofori was unsatisfied by the lack of control that musicians had over the volume level of the harpsichord. He is credited for switching out the plucking mechanism with a hammer to create the modern piano in around the year 1700.

https://www.yamaha.com/en/musical_instrument_guide/piano/structure/
www.pianopedagogues.com