Harmony
Progressions, cadences and functional harmony.
Harmony
How Cadences Work: Authentic, Plagal, Half and Deceptive
How cadences work in tonal music: why the authentic cadence closes most strongly, and how half, plagal and deceptive cadences change an ending.
HarmonyRoman Numerals Explained: Reading Chords in Any Key
Roman numeral analysis labels each chord by its scale degree and quality, so you can read progressions in any key and see how harmonic function works.