Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. This variation results in different atomic masses but does not significantly alter the chemical properties of the element. For example, carbon has several isotopes, including carbon-12 and carbon-14, with applications in areas such as radiocarbon dating. Isotopes can be stable or radioactive; the latter undergoes decay, releasing energy and particles over time. Their unique properties are exploited in various scientific and medical fields.