For questions about music written for piano, playing the piano, maintenance of a piano, or other general questions about pianos.
The musical instrument now called a piano used to be called a "pianoforte." It uses felt tipped hammers driven by keys on a keyboard to strike at strings. When it was originally developed it was able to be played both softly (piano is Italian for soft, and quiet passages will be noted with a small p on sheet music) and loudly (forte is Italian for hard, and loud passages will be noted with a small f on the sheet music), so the combination became the name of the instrument.
Typical modern pianos have 88 keys spanning from the pitches A0 through C8. The keys for C#/Db, D#/Eb, F#/Gb, G#/Ab, and A#/Bb are all set raised above the others and are smaller and coloured black to serve as a visual and tactile reference for players. They also often have a number of foot pedals which change the acoustic tone of the instrument in various ways.
In the 20th century, synthesizers and digital keyboards were invented that could be played like a piano, but which created their sounds entirely digitally. This not only greatly improved upon the portability and practicality of the piano, it allowed for a great range of different tones and electronic instrument sounds that could be played with almost identical technique to the acoustic pianos.