This book makes a study on Islamic State (IS or ISIS)- a Sunni based Jihadi group fighting in Iraq and Syria. Its leader Abu-Bakar al-Bagdadi declared him as caliph. Current study demonstrates answers of four questions regarding the leadership, tactics, relationship between leaderships' and tactics, and the governance of Islamic State (IS). To conduct this study ISIS related published data from 2011-2014 has been used. The analytical part of this study is divided into four major parts. The first part describes the conceptualization of ISIS's leadership. Moreover since the inception, ISIS had been using different types of terrorist tactics. Second part comprehensively addresses the these tactics. Furthermore, the relationship between changing patterns and strategies of leadership and operational tactics has bee analysez. Finally, the book has made a comprehensive analysis of the governance styles followed by the group in its captured areas of Iraq and Syria.