Providing up-to-date information for general readers as well as those well-informed about the Islamic State, this book offers an essential understanding of the rise of ISIS and its current influence in the Middle East as well as worldwide. ISIS—also referred to as ISIL, the Islamic State, or Daesh—began to assert its power and gain recognition for its militant and terroristic activities in April 2013. After the coordinated attacks in Paris on November 13th, 2015, ISIS has captured the full attention of observers in the West. This accessible book explains what ISIS is, what the group's goals are, what their members believe, and why their ranks are growing. Readers will gain an understanding of how ISIS is a unique group—one seeking to be the army of the righteous fighting to defeat the unbelievers and usher in the end of days—but that the extremist views of ISIS are an expression of a growing frustration with life in the Middle East and elsewhere shared by a larger community of non-state and post-state actors. The book provides an introduction that documents the origins of ISIS within the larger Al Qaeda organization during the Iraq War. The following chapters discuss the origins, development, and territorial expansion of ISIS in Syria and Iraq and examine the ideological motivations behind the emergence of ISIS, thereby enabling a nuanced understanding of the importance of ISIS in contemporary history. Other entries discuss individuals, events, and organizations that put ISIS in historical context in terms of contemporary events since the Iraq War into the present and explain the group's position within the complex conflict currently boiling in the Middle East.