Basic purpose of this lecture is to presentation on the Costs of Production. In this lecture, look for the answers to these questions, like, What is a production function, What is marginal product and How are they related. Here also focus on What are the various costs, and how are they related to each other and to output and How are costs different in the short run vs. the long run. Overall the major discussion is the particular marginal product of labor would be the increase in output coming from a one-unit increase in work, holding other inputs frequent. The marginal products connected with other inputs are defined similarly.