This document provides an introduction to engineering economy. It defines economics as the study of how limited resources are used to produce and distribute goods and services. It discusses microeconomics, which deals with individual decision-making, and macroeconomics, which looks at aggregate outcomes for an overall economy. Managerial economics applies economic principles to organizational decision-making, while engineering economics specifically evaluates the costs and benefits of engineering projects and systems. Decision-making involves reducing uncertainty to choose the best alternative based on available information. The quality of a decision depends on the process used, not the outcome. Engineering and public projects require structured decision-making approaches.