Explanation:

Subsistence farming, form of farming in which nearly all of  the crops or livestock raised are used to maintain the farmer and the farmer’s family, leaving little, if any, surplus for sale or trade. Preindustrial agricultural peoples throughout the world have traditionally practiced subsistence farming. Some of these peoples moved from site to site as they exhausted the soil at  each location. As urban centres grew, agricultural production became more specialized and commercial farming developed, with farmers producing a sizable surplus of certain crops, which they traded for manufactured goods or sold for cash. Shifting cultivation is an example of subsistence farming.