The production possibility frontier (PPF) is a graph that shows the maximum possible output combinations of two goods or services an economy can achieve when all resources are fully and efficiently employed.

Point X on the above PPF curve represents an inefficient allocation of resources, as there is some unemployment or underutilization of factors of production.

The economy can produce more of both consumer and capital goods by moving up along the curve towards point Y, which is the optimal or efficient point.

Point Z, on the other hand, represents an unattainable or impossible output combination, as it lies outside the PPF curve.