This document provides an overview of police intelligence and its history. It defines intelligence as deriving from the Latin word "intelligere" meaning to "pick out or discern." It discusses the organization, activities, and products of intelligence work. It then examines various historical figures and their contributions to developing intelligence techniques, including Sun Tzu, Frederick the Great, Sir Francis Walsingham, Napoleon Bonaparte, and Herbert Yardly. It also discusses important intelligence agencies like the Australian Secret Intelligence Service.