Islamic State significant event 2014 Fall of Mosul
The Islamic State (IS), also known as the Islamic State of Iraq and the Levant (ISIL; ), Islamic State of Iraq and Syria (ISIS; ), and by its Arabic acronym Da'ish or Daesh (داعش, Dāʿish, IPA: [ˈdaːʕɪʃ]), is a transnational militant Islamist terrorist group and former unrecognized quasi-state that follows the Salafi jihadist branch of Sunni Islam. 
It was founded by Abu Musab al-Zarqawi in 1999 and gained global prominence in 2014, when it captured a large amount of Iraqi territory,  and took advantage of the civil war in Syria to take control of chunks of territory in Eastern Syria. By the end of 2015, it held an area estimated to contain  eight to twelve million people stretching from western Iraq to eastern Syria, where it enforced its interpretation of Islamic law, administered an annual budget of more than US$1 billion and had more than 30,000 fighters under its command. By 2019 it had lost the last of its Middle Eastern territories and returned to  insurgency in the regions it once controlled, operating from remote hideouts,  and continuing its propaganda efforts.From 2003 to 2013, the group pledged allegiance to al-Qaeda (mostly under the name "Islamic State of Iraq") and participated in the Iraqi insurgency against the United States and its allies. The group changed its name again to "Islamic State of Iraq and Levant" for about a year, before proclaiming itself to be a worldwide caliphate, called simply the Islamic State (الدولة الإسلامية, ad-Dawlah al-Islāmiyah). As a caliphate, it demanded the religious, political, and military obedience of Muslims worldwide, despite the rejection of its legitimacy by mainstream Muslims and its statehood by the United Nations and various governments.For the next few years the Iraqi Armed Forces and the Syrian Democratic Forces beat back "the Islamic State" and degraded its financial and military infrastructure, assisted by advisors, weapons, training, supplies and  airstrikes by the U.S. coalition, and later by Russian airstrikes, bombings, cruise missile attacks and scorched-earth tactics across Syria, which focused mostly on razing opposition strongholds rather than IS bases. By March 2019, IS lost one of its last significant territories in the Middle East.
Designated a terrorist organisation by the United Nations and others, the group was known for its massive human rights abuses: genocide against Yazidis and Christians on a historic scale, systematic persecution of Shia Muslims; its videos of beheadings (and other kinds of executions) of soldiers, journalists, and aid workers; as well as its destruction of cultural heritage sites.As of November 2022 the leader of the "state" is reportedly Abu al-Husain al-Husaini al-Quraishi, its previous leaders having been killed in fighting or suicides.