The piano (also called the pianoforte) is a stringed keyboard musical percussion instrument, derived from the harpsichord and the clavichord. But it differs from its predecessors mainly in the introduction of a hammer-and-lever action that allows the player to modify the intensity of sound by the stronger or weaker touch of the fingers. For this reason, the earliest known model (1709) was called a gravicembalo col piano e forte (Italian for “harpsichord with soft and loud”). It was built by Bartolomeo Cristofori, a harpsichord maker of Florence, Italy, who is generally credited with its invention.
This instrument is extremely important because of its universality. A piano is categorized as a percussion instrument, although it’s used to produce a melody. The piano contains both treble and bass clef, and may simultaneously accent a percussion accompaniment.
When beginning to learn any instrument, most theory books use the piano as an example of octaves, pitch, and so on. This is because a piano best illustrates these principles on a linear plane, instead of a fretboard divided by six strings, each of which begins with a different note and pitch. The piano does not yield such a predicament, simply because the notes repeat themselves in the full range of octaves without change, unlike a guitar. On a full octave guitar, the last fret is the same note if that string was open, but does not go to the next note on the next string up in linear succession, as does a piano. In other words, the low “E” string on a full octave guitar is an “E” whether open or fretted on the 24th fret, and the next acceding note, “F” is not the next open string note – rather, the next string is the “A” string and therefore produces an “A” when open.
The piano is also a good example of learning basic music theory because of its ability to stand alone for entire compositions (by virtue of its history in classical music). Most classical guitar is transposed from piano and does not have the same awe-invoking effect as a piano, but allows the composition to be delivered via another instrument.
The piano is very essential to learning music theory not only for the above reasons but because of the voicing(s) that are capable of being played simultaneously – an expert pianist can play four voices proficiently. This is not actually possible on the guitar because the guitar can only play in the treble clef and cannot truly mimic the bass clef played on the piano. Furthermore, a guitarist can only play chords or articulate at one time, while a pianist may do both concurrently.