One of the most widely used is potassium-argon dating (K-Ar dating).
Potassium-40 is a radioactive isotope of potassium that decays into argon-40.
Techniques include tree rings in timbers, radiocarbon dating of wood or bones, and trapped charge dating methods such as thermoluminescence dating of glazed ceramics.
Coins found in excavations may have their production date written on them, or there may be written records describing the coin and when it was used, allowing the site to be associated with a particular calendar year.
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology.
Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy.
Thus dating that particular tree does not necessarily indicate when the fire burned or the structure was built.
For this reason, many archaeologists prefer to use samples from short-lived plants for radiocarbon dating.
This technique is based on the principle that all objects absorb radiation from the environment.
This process frees electrons within minerals that remain caught within the item.
This is a radiometric technique since it is based on radioactive decay.