State about Production theory

Production theory assists in determining the size of firm and level of production. It clarifies the relationship between marginal and average costs and production. It highlights how a change in production can bring about a parallel change in marginal and average costs. Production theory also  deals with many other issues like conditions leading to decrease or increase in costs, changes in entire production when one factor of production is varied and others are kept constant, substitution of one factor with another whereas keeping all increased concurrently and methods of achieving optimum production.