A back garden, or backyard in America, is on the far side of the house from the public road. Unlike a front garden or yard, a back garden is normally used as a social space for family and friends. If the family are keen gardeners it will be used for ornamental horticulture. Other typical uses include swimming pools, barbecues, vegetable growing, garden games and hobbies.
English terrace housing with back gardens
American backyard with swimming pool
American backyard without fencing between properties
American backyard treated as a patio