That’s a deeeeeeeep question thanks! Have you ever heard of Albert Einstein!? He asked himself this very question and came up with the equation E=MC2. It’s very complicated but it basically means that all matter is energy and all energy is matter! Freaky eh!? But it’s true. That’s where nuclear energy comes from. A very small amount of matter is converted to energy. And a LOT of it!
So you, sitting there typing this message are a big bundle of energy! So is the desk, the computer and the air you’re breathing! Electrifying!