Chord Progressions

Chord progressions are usually expressed by Roman numerals in Classical music theory.

While numbers aren’t able to differentiate between major and minor chords, Roman numerals are. To demonstrate, let’s go back to our C Major scale and build triads on each of the scale degrees:

Notice how some of the Roman numerals are uppercase and others are lowercase.

Uppercase Roman numerals represent major chords.
Lowercase Roman numerals represent minor chords.

The quality of the chords will depend on the key. For example, let’s look at A Minor: