Wage theories explain how wages are determined. Historically, the subsistence theory viewed wages as only enough to provide basic sustenance. Modern wage theory sees wages as the price of labor set by the interaction of labor demand and supply in the market. Demand for labor depends on factors like productivity, technology, and demand for products, while supply relates to the number of available workers. Under competitive conditions, equilibrium wages are reached at the point where the labor demand and supply curves intersect.