Who is ISIS? What have they done? What do they want to accomplish? Where do they come from? These are the questions anybody should ask, who's not informed of the Sunni jihadist organization located in Syria and Iraq.
ISIS stands for Islamic State of Iraq and Syria, and is a self-proclaimed caliphate. A caliphate is an Islamic state that is headed by a caliph, a man who has extreme religious and political power from being chosen by Allah. The man who's in reign of ISIS, Abu Bakr al-Baghdadi (Caliph Ibrahim), self-proclaimed himself as a caliph, and is establishing ISIS to claim religious authority over all Muslims across the world. ISIS hopes to establish a world-wide caliphate, where Muslims will create a world-wide government under the path of jihad. That path, however, is very unlikely to be accomplished. It's pursued by Islamic extremists that commit atrocities and war crimes, and the majority of the Islamic audience do not consider that vision.
ISIS originated in Iraq at around 2004 (before undergoing numerous name changes), shortly after the invasion led by the USA in 2003. Many of today's leaders and military strategy advisors for ISIS, gained experience in guerrilla warfare against the American military. After the American military withdrew its last troops from Iraq in 2011, ISIS took advantage of several situations. The Iraqi insurgency between the Shia-central government and Sunni-militant groups continued at a larger scale. Syria became involved in a civil war, and there was no American military presence to interfere. ISIS took control of several regions in Iraq, and began to expand in Syria, establishing its headquarters in Ar-Raqqah, Syria. They've expanded to about 100,000 fighters, and that number continues to grow, as Syrian rebels who have originally fought against ISIS, are giving in to their side. They're noticing that the Sunni-extremist group is gaining the upper hand in its conquered territories, and would be involved in an inevitable loss.
ISIS is a force to be reckoned with. They're militarily superior to practically every rebel group that exists in the Middle East, they operate businesses in their controlled territories to generate wealth for funding their campaigns. They're able to (and do) pay their fighters $400-500 a month, and are developing traits that are affiliated with mafia and gang operations. What can we do about it?
You've been informed, form an opinion.