Internal auditing involves independently and objectively evaluating an organization's operations to improve efficiency and effectiveness. It assesses risk management, controls, and governance processes to help the organization achieve its objectives. Internal auditing adds value by bringing a systematic approach to evaluate and improve these processes. The document then provides examples of how internal audit evaluates areas like operational expenses, investments, and revenue leakage at a cable TV company. It examines processes for purchasing, stores management, and controls over expenses, capital expenditures, and revenue streams.