ELI5: What is the difference between major and minor chords?

The main difference between major and minor chords is that major chords sound happy, bright, and cheerful, while minor chords sound sad, dark, and mysterious.

To understand why, imagine building a sandwich:

• A major chord is like a sandwich made with your favorite ingredients on a sunny day. It feels complete, sweet, and gives you a burst of energy.
• A minor chord is almost the exact same sandwich, but with one tiny twist: you swapped the sweet jam for a sour pickle. That single tiny change makes the whole bite taste completely different.

• In a major chord, the middle note sits a little bit higher. That tiny step up gives the music an open, smiling, and triumphant feeling, like winning a gold medal or playing outside on a warm summer morning.
• In a minor chord, that middle note drops down just a tiny bit lower. That small step down pulls the mood into something cozy, rainy, or a little spooky, like watching thunderstorms from your window or tiptoeing through an old attic.

• Happy birthday songs and national anthems use major chords because they want you to feel joyful, proud, and ready to celebrate.
• Spooky Halloween music and the dramatic music in movie scenes where a character loses something special use minor chords to make you feel suspense or sympathy.