A private protected area, also known as a private reserve, is not an official category within IUCN's Protected Area guidelines, but includes those protected areas that fall under geographical space that is privately owned, 'kept aside' for public benefit, and will be likely to fall into any one of the IUCN Protected Area Management Categories.
The IUCN defines a private protected area as “a land parcel of any size that is...":
A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, funga, or features of geological or other special interest, which is reserved and managed for purposes of conservation and to provide special opportunities for study or research. They may be designated by government institutions in some countries, or by private landowners, such as charities and research institutions. Nature reserves fall into different IUCN categories depending on the level of protection afforded by local laws. Normally it is more strictly protected than a nature park. Various jurisdictions may use other terminology, such as ecological protection area or private protected area in legislation and in official titles of the reserves.