something that is necessary for human survival, such as food, warmth or shelter.

inputs into the production process, land, capital and enterprise

how best to make the decisions about the allocations of scarce resources among competing uses so as to maximise human happiness and welfare.

when the available economic resources are used to produce the combination of goods and services that best matches people's tastes and preferences.

when a firm's average cost is at the bottom of the average cost curve. Lowest possible cost.