This short textbook seeks to provide an conceptual, historical, contemporary and social understanding of the 'police', one of the key social and legal institutions of the modern state. Police are an integral part of the criminal justice system. On completion of the book, students will have knowledge of the relationship between police, crime and society; the workings, power and discretion of the police; the relationship between policing, social policy and political ideologies. The book is a brief but critical introduction to the main issues facing police officers in the 21st Century.