This paper is based on presenting and defining the term and concept of terrorism and describing the Islamic State of Iraq and the Levant (ISIL) so that this threat, one of the biggest threats of today, would become clearer and more understandable. The first part of the paper is focused on presenting the fenomenon of terrorism, it's historical background and development with which we stop at today and the level of development reached so far. The social causes of terrorism are instigated and two types of terrorism are described more detaily: religious terrorism and cyber terrorism, since ISIL's terrorism comes under those two categories. The paper tries to get an answer on the question who becomes a terrorist and why, it researches the profiles of people and additionally of women in terrorism, the process of entering, experiencing and going through a terrorist organization, it expains how such an organization functions, it's influence and dinamics on a broader group of people and followers. At the end of the first part there is a short review on the psychology of group violence since we can take into consideration that terrorism could be observed and studied through such a view – through one group's violence over another. After the concept of terrorism is expained, the second part of the paper switches it's focus on the Islamic State of Iraq and the Levant, the main subject of this paper. ISIL today represents a threat which has grown stronger and stronger in the last few years and which brings violence and a rule of law which was thought to be forgotten and left in the past. Despite it's brutality, ISIL is recognized as the most organized, dangerous and richest terrorist organization in history and it's effectiveness cannot be denied in spite it's cruelty and unacceptability of it's actions. The chapter starts with a historical overview which explains how ISIL arosed and from what as well as on which ideas, religious explanations, norms and experiences it is based. Different profiles of ISIL's fighters were researched and the paper lists „cathegories“ in which they belong, where do they come from, what motivates them to join, how are they recruited. The paper also provides a short overview on the cathegory and issues concerning women and children under ISIL rulership. Further on, the paper presents the relationship between ISIL and modern technology, something that detects ISIL as the most artful and up-to-date organization which makes the best usage of possibilities of modern technology than any other terrorist organization before. The idea that a terrorist organization aspires to establish it's own state is a situation which the world faces for the first time and gradually addapts to it and learns how to handle such a threat, how to fight it. Therefore, it is important to get to know and understand the theoretical basis as well as all aspects of ISIL and the way it functions and performs. In one hand that is a way to get acquainted with the enemy (as possibly it's flaws) and on the other hand it's a way to fight against newly risen prejudice towards muslims and islam in general.