Absolute dating methods enable us to give actual age to a fossil, artefact or rock (in years) – examples of absolute dating methods include carbon-14 dating, potassium-argon dating, and tree-ring dating.

Absolute dating methods depend on the regular repetition of any event, such as the decay of unstable nuclei to stable nuclei.

The proportion of a radioactive isotope in a sample of material can be measured, and by knowing the half-life of a particular radio-isotope, the sample's age can be worked out.