Hi, I'm new both to this forum and to physics in general. Here's hoping I've posted in the right place.... I'm basically trying to understand the difference between energy and matter and how one can become the other. Please bear with me, I'm a total layman and can't seem to get a definitive answer anywhere online. So I guess I get the basics: Matter is made up of atoms which are made up of subatomic particles. But the added mass of the individual particles doesn't add up to the total mass of the atom. The remaining mass is made up of energy. The energy that was needed to bind the particles into a nucleus is converted into mass when the strong force takes over from the EM force. Which means that matter is partly converted energy.... But what about the particles that make up the atom? Were the protons, electrons and neutrons matter before they became bound together? Or were these particles themselves energy to begin with? The reason I'm confused is because free electrons are supposed to be electrical energy, not matter. And, seeing as photons are free moving and they are energy, I'm assuming that subatomic particles are energy until they are bound into an atom, making them matter.....? So essentially I'm asking, are protons, electrons and neutrons always matter, or can they be energy as well? Sorry if this is a dumb question. I'm certainly no physicist, just curious.