This document provides an introduction to microeconomics concepts including economic efficiency, opportunity cost, and production possibilities curves (PPC). It uses a simplified example of an economy with 100 workers and 50 nets that can be used to produce fish or berries. The PPC shows the different combinations of fish and berries that can be produced and how the rate of transformation, or opportunity cost, changes as resources are reallocated between the two goods. When technology improves to make nets more productive for berry production, the PPC will shift outward, allowing more total production.