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 Daesh, is a transnational Salafi jihadist militant organisation and unrecognised quasi-state. ISIL occupied significant territory in Iraq and Syria in 2013, but lost most of it in 2017 and 2019. In 2014, the group proclaimed itself to be a worldwide caliphate, and claimed religious and political authority over all Muslims worldwide, a claim not accepted by the vast majority of Muslims.
https://en.wikipedia.org/wiki/Islamic_State