Microeconomics looks at interactions through item-by-item markets, given scarcity and government ordinance. A given market might be for a product, say fresh corn, or the services of a factor of output, say bricklaying. The theory considers aggregates of amount demanded by buyers and amount supplied by sellers at apiece possible price per unit. It weaves these together to describe how the market may reach balance as to price and quantity or respond to market changes over time.

This is generally termed supply and demand analysis. Market structures, specified perfect competition and monopoly, are examined as to deductions for behavior and economic efficiency. Analysis of change in a single market frequently proceeds from the simplifying assumption that behavioral relations in other markets remain unchanged, that's, partial-equilibrium analysis.

General-equilibrium theory allows for changes in different markets and totals across all markets, including their movements and interactions towards balance.