This chapter reviews the inputs that define the net demand for the goods required in Rome, including the products consumed, the area and the number of people supplied, and the average dietary intake. Supply in antiquity, like today, was governed by product availability as well as freight and production costs. The essential consideration was the ability of the hinterland to grow enough produce to supply the energy needs of both the local population and the city at competitive market prices. The three energy sources, typical of pre-industrial agrarian societies, like Rome, were food, wood for heating, and animal fodder. During the Empire, there were different social strata in Rome with less than two per cent of people being in the upper echelons of society. The other 98 per cent comprised the non-elite, including commoners, slaves, and freed people whose status, whether social, economic, or legal, prevented them from joining the upper ranks.