In this course we explore consumer theory and the main results that can be obtained in the light of rationality of economic agents. Under the factors we focus the analysis on market labor market and analyze and compare results by key depending on the structure of market considered. We study general equilibrium models, in which all markets balance, and analyze the properties of optimality of equilibrium (2 fundamental theorems of Welfare) economy. Finally we study issues that arise when one wants to analyze the Welfare associated with different resource allocations.