A nature reserve (natural reserve, nature preserve, natural preserve) is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research. Nature reserves may be designated by government institutions in some countries, or by private landowners, such as charities and research institutions, regardless of nationality. Nature reserves fall into different IUCN categories depending on the level of protection afforded by local laws.

King Devanampiya Tissa of Sri Lanka established one of the world's earliest wildlife sanctuaries in the 3rd century BC. However, dating back to antiquity there are various cultural practices that equate roughly to the establishment and maintaining of reserved areas for biota including fish, waterfowl and other animals. These would often have a religious underpinning—for example the 'evil forest' areas of West Africa were forbidden to humans, who were threatened with spiritual attack if they went there. Sacred areas taboo from human entry to fishing and are known by many ancient cultures worldwide.