Abstract: There are provided visual displays for graphically showing on a visual representation of a guitar fretboard a location relationship between a given chord and its chord tones as well as for graphically showing on a visual representation of a guitar fretboard a location relationship between a given position and its scale tones. The present disclosure also relates to a method for visually expressing, on a visual representation of a guitar fretboard, the location relationship between a given chord, its chord tones and its scale tones, in a given key; a music notation method for representing a location relationship between a given chord, its chord tones and the scale tones of the scale to which said given chord belong, on a visual representation of at least a portion of a guitar fretboard; and visual display for expressing musical harmonic functions.