Detailed harmony: Roman numerals, function, and progression.

1. Roman numerals

Roman numerals label chords by scale degree. In C major, C major is I, D minor is ii, E minor is iii, F major is IV, G major is V, A minor is vi, and B diminished is vii°. Uppercase usually means major, lowercase means minor, and the diminished symbol means diminished.

2. Tonic, predominant, and dominant

Tonic chords feel stable and centered. Predominant chords move away from tonic and prepare the dominant. Dominant chords create tension that strongly wants to resolve back to tonic. A basic classical pathway is tonic → predominant → dominant → tonic.

3. Progressions

A progression is a sequence of chords. Some progressions are common because they balance stability, motion, and resolution. The progression I-V-vi-IV is common in popular music. The progression ii-V-I is essential in jazz. The progression I-IV-V-I is a foundational tonal pattern.