Carbon-14 is a weakly radioactive isotope of Carbon; also known as radiocarbon, it is an isotopic chronometer. C-14 dating is only applicable to organic and some inorganic materials (not applicable to metals).

How is the isotope carbon-14 used for radioactive dating?

Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.