ELI5: Explain Like I'm 5

Proton

A proton is a tiny particle, like a very small piece of something. It's like a tiny dot and it lives in the center of an atom, which is the smallest unit of matter. Atoms are all around us, they make up everything! A proton has a positive charge, which means that it has a lot of energy - this energy helps to hold the atom together, and it's what makes stuff like us stay together instead of flying apart!