Quarks are elementary particles and fundamental constituents of matter. They combine to form composite particles called hadrons, which include protons and neutrons, the components of atomic nuclei. Quarks have various intrinsic properties, including electric charge, mass, color charge, and spin. They are the only elementary particles in the Standard Model of particle physics to experience all four fundamental interactions, also known as fundamental forces (electromagnetism, gravitation, strong interaction, and weak interaction) . Quarks are spin-1/2 particles, which means they are fermions according to the spin–statistics theorem. They are subject to the Pauli exclusion principle, which states that no two identical fermions can simultaneously occupy the same quantum state.

There are six types of quarks, known as flavors: up, down, strange, charm, bottom, and top. Up and down quarks are the most common and combine to form protons and neutrons. Quarks cannot exist independently but as a constituent part of matter. They are always bound together by the strong nuclear force, which allows them to form composite particles called hadrons. Particles made of two quarks are called mesons, and particles made of three quarks are called baryons.

To fit into quantum physics theory, the behavior of quarks is governed by a model called quantum chromodynamics (QCD) . The "chromo" in the name refers to "color," which is not as in red, green, or blue, but the name given to a particular quantum number that quarks possess. Color plays the same role in the strong force as electric charge plays in the electromagnetic force. The strong force that binds quarks inside hadrons is carried by another kind of tiny elementary particle called gluons, which are exchanged between the quarks.

In summary, quarks are elementary particles that combine to form composite particles called hadrons, which include protons and neutrons. They have various intrinsic properties, including electric charg...