The Latin word "Radis" or "roots" means buried at the root of fundamental. It shows that a radical is a person who wishes to bring the fundamental, political and social change and therefore radicalization is a mindset by which people adopt extreme views and beliefs, being prepared to take violent measures for political and religious gains. Wilner and Duboulos define radicalization as the following: "Radicalization is a personal process in which individuals adopt extreme political, social and religious ideas and aspirations and where the attainment of particular goals justifies the use of indiscriminate violence, it is both a mental and emotional process that prepares and motivates and individual to pursue violent behavior. It is interesting to note that radicalization does not always lead to violence in the initial stages. So, the slow process of radicalization may take place while there is no realization of the gravity of the situation. In contemporary discourse of religious radicalization, religion is often believed to be at the center of one's radicalization. I hope readers will enjoy reading this valuable book. www.NoorDahri.com