This volume addresses in various ways the four central categories of question that determine our understanding of terrorism: definition, causation, consequences and response. It therefore addresses unquestionably major subjects. It also does so with a sharp eye to the wider phenomena to which radicalization, terrorism, counter-terrorism and de-radicalization are related, including gender, ethnicity, religion, complex historical inheritances, migration, education, economics and societal resilience. So the arguments in the book evince an appropriate sense of the analytical complexity and interwovenness that are required and declined according to the experiences in fighting against terrorism and radicalisation of experts of three different countries: Italy, a traditional Christian society, Azerbaijan, a Shia but secular society, and Algeria, a Sunni society.