Why do chords sound happy or sad? Major vs minor explained

A chord is notes stacked in steps: a root, a third and a fifth. The only difference between major and minor is the third. In a major chord it's 4 semitones above the root and sounds bright. In a minor chord it's 3 semitones above the root and sounds sad or moody. One note changes the whole feeling.

How to do it

1. Pick a root note, for example C.
2. Count 4 semitones up for a major third (E) and 7 semitones up for the fifth (G). That's C major.
3. Move the third down one semitone (E♭). That's C minor.
4. Play them one after the other and listen to the mood change.
5. Use the same counting on any root to build any major or minor chord.

Why it works

The third decides the chord's colour because it sits right in the middle and defines how the root and fifth relate. The root and fifth alone (a power chord) sound neither happy nor sad.

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