What is harmony? Why is it important? Why a pianist should learn it?
I like to define harmony as the subject that makes the various reasons of music understood.
Music is full of rules and these rules are precisely determined by harmony.
If you want to express yourself in an authentic way, be able to play a piece or compose your own songs at your best, you must absolutely learn all these rules and try to make them your own.
In music we have three fundamental elements: melody, rhythm and harmony.
Rhythm is an obvious concept, as is melody, a linear succession of notes, while when we have two or more superimposed notes, harmony is created. To have harmony you don't necessarily need to create a chord, there can be two instruments playing two different melodies, or there can also be two melodies that are contrasting with each other and create dissonances, but in that moment harmony is still being created.
If melody is the horizontal element, harmony is the vertical one.
This thing is well represented on the scores: when we play several chords one after the other we are creating a harmonic sequence. On each of these chords we can play a certain scale, or more scales, that can be used to improvise or to create melodies.
The connection between the chord and the scale is determined by harmony.
If we take one or more chords of a sequence and replace them with other chords we create new, more distant and more unexpected sonorities; also in this case it is the rules of harmony that tell us how we can replace a chord.
Harmony therefore explains how the pieces work, teaches us to recognize the successions of chords and to understand the relationships between them.
Learning harmony will make learning the repertoire by heart much easier and faster, especially if it is pop, rock and jazz songs.
The knowledge of the concepts of tension / resolution, and the quantity of these elements that a succession of chords can create, will lead you to define a piece on a harmonic level, to improvise on it with more clarity, to be able to create more effective arrangements and to have a series of options that you can use to compose your songs.
Harmony study is a kind of dividing line between amateur musicians, who don't ask questions and just want to get their hands on the instrument to play music, and those musicians who instead want to study more deeply, want to become professionals or have a great desire to understand what is behind the music, even if they play only for hobby and passion.
Knowing harmony will therefore allow you to understand what you are doing while playing, and to do it better.