Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In economics, a production–possibility frontier (PPF), sometimes called a production–possibility curve, production-possibility boundary or product transformation curve, is a graph that compares the production rates of two commodities that use the same fixed total of the factors of production. Graphically bounding the production set, the PPF curve shows the maximum specified production level of one commodity that results given the production level of the other. By doing so, it defines productive efficiency in the context of that production set. A period of time is specified as well as the production technologies. The commodity compared can either be a good or a service.