A nucleon is a subatomic particle found in the nucleus of an atom. There are two types of nucleons: protons and neutrons. Protons carry a positive electric charge, while neutrons are neutral. Together, they make up the mass of an atom and play a crucial role in determining its identity and stability. Nucleons are held together in the nucleus by the strong nuclear force, which is one of the four fundamental forces of nature. This force is mediated by particles called gluons. The number of protons in a nucleus defines the element, while the total number of nucleons determines its isotope.