Quarks are elementary particles and fundamental constituents of matter, forming the building blocks of protons and neutrons. They come in six flavors: up, down, charm, strange, top, and bottom, and they combine in groups to create larger particles known as hadrons. Quarks are held together by the strong force, mediated by particles called gluons. This interaction is described by the theory of quantum chromodynamics (QCD). Understanding quarks is essential for comprehending the fundamental structure of the universe and the forces that govern it.