Absolute dating is the process of determining an age on a specified time scale in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty and precision. Absolute dating provides a numerical age or range in contrast with relative dating which places events in order without any measure of the age between events. In archeology, absolute dating is usually based on the physical, chemical, and life properties of the materials of artifacts, buildings, or other items that have been modified by humans and by historical associations with materials with known dates. 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 their may be written records describing the coin and when it was used, allowing the site to be associated with a particular calendar year.