A is the "home base" of a song, and a Scale is the sequence of notes within that key.
Before you can build a scale, you need to know the distance between notes.
The most basic chords, built using the 1st, 3rd, and 5th notes of a scale.
Sound "sad" or "serious." The natural minor formula is: W–H–W–W–H–W–W .
A Major triad has a "large" interval (Major 3rd) at the bottom, while a Minor triad has a "small" interval (Minor 3rd).