Subatomic particles are fundamental constituents of matter that possess mass and electric charge, existing within the atomic nucleus or orbiting it. They are categorized into different groups, including fermions, such as quarks and leptons, and bosons. Quarks are the constituents that combine to form composite particles like protons and neutrons, while leptons, such as the electron, exist independently. The interactions between these particles—governed by fundamental forces like electromagnetism and the strong and weak nuclear forces—determine the structure, stability, and chemical behavior of all known matter. The study of these particles is central to modern physics, aiming to define the most basic building blocks of the universe and the mechanisms by which they interact.