Carbon $14$ dating is used to estimate the age of an archeological specimen.

The unstable and radioactive carbon 14 called radiocarbon is a naturally occurring isotope of the element carbon. When a living thing dies, it stopes interacting with the biosphere,  and the carbon 14 in it remains unaffected by the biosphere but will naturally undergoes decay. Decay of carbon 14 takes thousands of years and it is this wonder of nature that forms the basis of radiocarbon dating any made this carbon 14 analysis a powerful tool.