A reference card. The dominant seventh (last lesson) is the one that runs Classical music.
There are four other seventh-chord types — you'll meet them properly in jazz and Romantic
harmony, but it's worth knowing they exist and roughly what each sounds like.
Chord
Recipe
Sound
Where you meet it
Major 7th (Cmaj7)
major triad + major 7th
lush, still, slightly dreamy
jazz; Romantic colour
Minor 7th (Cm7)
minor triad + minor 7th
mellow, soft-edged
jazz; the ii7 chord
Dominant 7th (C7)
major triad + minor 7th
wants to move
everywhere in tonal music — the one that counts
Half-diminished 7th (Cø7)
diminished triad + minor 7th
tense, aching, unresolved
ii°7 in a minor key; vii7 in major
Fully diminished 7th (C°7)
diminished triad + diminished 7th
maximum tension, no clear home
vii°7 in minor; a pivot to anywhere
72 bpm
Three seventh chords on C, as broken chords: major 7 (lush), dominant 7 (wants to move), minor 7 (mellow). Play the three bars and hear the colour shift. Only the dominant 7th is core for this stage.
Where you land
For Stage 4: recognise a four-note stacked chord as a seventh chord, and know that if it's
built on ^5 of the key and it's straining home, it's the dominant 7th. The rest is a
vocabulary you'll build later.