Roman numerals

Roman numerals are often used for chords or scale degrees instead of their alphabetical name. This can help you think of their position relative to the key and to each other.

In a major key, the three major chords are:

I   - tonic
IV  - subdominant
V   - dominant

Minor chords are usually lower case:

ii  - supertonic
iii - mediant
vi  - submediant (relative minor)

For example, say you have these chords in C major:

C  Am  F   G  C

In Roman numerals this would be:

I  vi  IV  V  I

Read more: Roman numerals