Chord Analysis - Roman Numerals
In order to discuss the ways chords interact with each other, we must first give them names. If we begin with a major or minor scale, a triad can be built on each scale degree using the pitches that are available in that scale:
C Major Scale with Chords and Roman Numerals
A Minor Scale with Chords and Roman Numerals
Just as the scale degrees are numbered, so are the chords built on these scale degrees. Instead of Arabic numbers (1, 2, 3...), we use Roman numerals (I, II, III...) to mark these chords. For major triads we use upper case (I, IV, V in major), for minor triads we use lower case (ii, iii, vi in major), for diminished triads we use lower case and a small circle (example: vii°), and for augmented triads we use upper case and a plus sign (example: VI+).
Notice that the chord built on the tonic note in a major scale is major (I), and in a minor scale it is minor (i).