This document provides an introduction to chemical reaction engineering (CRE). CRE studies the rates and mechanisms of chemical reactions and the design of reactors. It discusses various reactor types including batch, continuously stirred tank reactor (CSTR), plug flow reactor (PFR), and packed bed reactor (PBR). The general mole balance equation is presented and applied to these different reactor configurations. Industries that rely heavily on CRE principles include chemical, pharmaceutical, and microelectronics.