Nucleons are the particles found in the nucleus of an atom. They include two types: protons, which have a positive charge, and neutrons, which have no charge. Together, these particles make up the mass of an atom and play a crucial role in determining its identity and stability. The number of protons in a nucleus defines the element, while the number of neutrons can vary, leading to different isotopes of the same element. Nucleons are held together by the strong nuclear force, one of the four fundamental forces in nature, which overcomes the repulsion between the positively charged protons.