This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book examines the several strands of UK’s deradicalisation efforts. It examines both Palestinian militia groups as well as right-wing ultra-orthodox Jews, who have been the major perpetrators of terrorism in Israel since its formation in 1967. The book discusses the state’s rehabilitation efforts, which have largely been focused on rehabilitating local youth before releasing them back to society. It examines Operation Safe Corridor as a counter-terrorism strategy through reviewing documents regulating Nigeria’s efforts at combating the scourge of terrorism and violent extremism. The book discusses rehabilitation policies adopted in Thailand, focusing on prison-based rehabilitation programmes conducted by the Department of Correction for security offenders. It reviews cases involving individuals who committed or attempted to commit acts of mass violence. The book provides a brief overview of the terrorist rehabilitation programmes in Spain and its contexts and challenges.