Among many religions, a feast is a set of celebrations in honour of God or gods. A feast and a festival are historically interchangeable. Most religions have festivals that recur annually and some, such as Passover, Easter and Eid al-Adha are moveable feasts – that is, those that are determined either by lunar or agricultural cycles or the calendar in use at the time. The Sed festival, for example, celebrated the thirtieth year of an Egyptian pharaoh's rule and then every three (or four in one case) years after that. Among the Ashantis, most of their traditional festivals are linked to gazette sites which are believed to be sacred with several rich biological resources in their pristine forms. Thus, the annual commemoration of the festivals helps in maintaining the buoyancy of the conserved natural site, assisting in biodiversity conservation.