Perfect fifth

Imagine you are playing with your musical toys. You have two toy notes, let's call them "A" and "E". If you play "A" and then play "E" right after, you will hear a nice sound that makes you feel happy and calm, like when you have your favorite toy with you. This special sound is called a perfect fifth.

It's like a musical high five between "A" and "E", and it always sounds good to your ears. It's like two friends who give each other high fives and feel happy together. It's a special relationship between two notes that is important in music.

So, when you hear music and you feel happy and calm, it's probably because you are hearing some perfect fifths in it, just like the two notes "A" and "E" that you played with your musical toys.