"In 2014 the Islamic State - also known as ISIS, or ISIL - seemingly appeared out of nowhere, capturing large swathes of territory in war-torn Syria and rushing across the border into Iraq and taking over the second-largest city in the country, Mosul. Then came a flurry of videos showing Western journalists being beheaded by the group and stories of young people leaving their homes in the Middle East, Europe, and the United States to fight with the Islamic State. What is the Islamic State? Is it a threat as potent and large as Al Qaeda in the early 2000s? Charles R. Lister, a Brookings fellow and journalist with long experience in the region, provides answers to these and other questions in The Islamic State: A Brief Introduction. He shows that IS is not a new phenomenon but has long historical roots in the region and has evolved from a small terrorist group into a functional state. He explains how it has also become a savvy propagandist, making use of social media both to trumpet its conquests and brutality and to attract adherents. And the book weighs how the West and regional powers need to act to ensure that IS will not, as its slogan proclaims, continue to be ""lasting and expanding""."