Jihadism is a neologism for militant Islamic movements that are perceived as existentially threatening to the West. It has been applied to various insurgent Islamic extremist, militant Islamist, and terrorist individuals and organizations whose ideologies are based on the Islamic notion of jihad. It has also been applied to various Islamic empires in history, such as the Umayyad Caliphate and the Ottoman Empire, who extensively campaigned against non-Muslim nations in the name of jihad.

The Islamic State (IS), also known as the Islamic State of Iraq and the Levant (ISIL), the Islamic State of Iraq and Syria (ISIS) and by its Arabic acronym Daesh, is a transnational Salafi jihadist group and a former unrecognised quasi-state. Its origins were in the Jai'sh al-Taifa al-Mansurah organization founded by Abu Omar al-Baghdadi in 2004, which fought alongside al-Qaeda during the Iraqi insurgency. The group gained global prominence in 2014, when its militants successfully captured large territories in northwestern Iraq and eastern Syria, taking advantage of the ongoing Syrian civil war. By the end of 2015, it ruled an area with an estimated population of twelve million people, where it enforced its extremist interpretation of Islamic law, managed an annual budget exceeding US$1 billion, and commanded more than 30,000 fighters.