Chronology is the science of dating involving the accurate placing of events in time and the definition of suitable timescales. In Christian societies, events are dated in years before (BC) or after (AD – Anno Domini) the traditional birth date of Christ. In scientific use, dates are often given BP (Before Present). In archaeology, dating techniques include dendrochronology and radiocarbon dating. In geology, rock strata are related to the geological time scale by examination of the fossils they contain.