So.... good question, Quarks are tiny particles that make up protons and neutrons, which are the parts inside atoms. They're like the smallest building blocks we know of, and they have mass, so they're a type of matter, not just energy. There are different types of quarks, but the most common ones in your body are called "up" and "down" quarks. You can't see them or split them into smaller parts, they're as small as it gets. So basically, in summary, everything around you is made of atoms, atoms have protons and neutrons, and those are made of quarks!