Primary sector.

The goods of the Earth are commonly categorized as animal, vegetable, or mineral. These must be processed to become the human essentials of food, clothing, and shelter. Economists generally divide the stages of this processing or transforming into three sectors: primary, secondary, and tertiary. The first classifies activities that produce raw materials; the second consists of manufacturing activities that change materials into usable products; and the third provides services to sustain the economic processes.