A hadron is a type of subatomic particle that is made up of quarks, which are fundamental particles. Hadrons are categorized into two main groups: baryons and mesons. Baryons, like protons and neutrons, consist of three quarks, while mesons are made of one quark and one antiquark. Hadrons are held together by the strong nuclear force, which is mediated by particles called gluons. Hadrons play a crucial role in the structure of atomic nuclei. They are responsible for the mass of atoms and contribute to the interactions that occur within the nucleus. Understanding hadrons is essential for studying particle physics and the fundamental forces of nature, as they are key components in the Standard Model of particle physics.