1. What is PPC?
In economics, a production–possibility frontier (PPF), sometimes called a production–possibility curve, production-possibility boundary or product transformation curve, is a graph that shows the various combinations of amounts that two commodities could produce using the same fixed total amount of each of the factors of production. Graphically bounding the production set for fixed input quantities, the PPF curve shows the maximum possible production level of one commodity for any given production level of the other, given the existing state of technology. By doing so, it defines productive efficiency in the context of that production set: a point on the frontier indicates efficient use of the available inputs, while a point beneath the curve indicates inefficiency. A period of time is specified as well as the production technologies and amounts of inputs available. The commodities compared can either be goods or services.
The Production Possibility Frontier (PPF) is an economics term referring to a graphical representation of the possible combinations or rates that two different commodities will be produced at given the same amount of resources, manpower, and other factors of production available within a certain period of time. Production Possibility Curve (PPC) is simply another term used to refer to this. Other terms used in the same way are Production Possibility Boundary and transformation curve.

2. How is the shape of PPC?
The production–possibility frontier can be constructed from the contract curve in an Edgeworth production box diagram of factor intensity. The example used above (which demonstrates increasing opportunity costs, with a curve concave from the origin) is the most common form of PPF. It represents a disparity in the factor intensities and technologies of the two production sectors. That is, as an economy specializes more