Isis is an offshoot of Al-Qaeda. Isis purpose is 2 create a caliphate. Salafi is an ultraconservative form of Islam, that's what they follow. They have been raising hell in Asia and Africa. They have a billion dollars worth of assets. They have been helped and hindered by various countries and organizations.
Isis splintered off from Al-Qaeda in Iraq. They were defeated in 2007. Later, they regrouped and went into Syria during the Arab Spring. They increased their ranks by setting Iraqi prisoners free. Al-Qaeda fell out with them in 2014., because Isis was too brutal.
Purpose
They want 2 create their own Islamic nation. They use to rule central Iraq, but not anymore. The Iraqi people were afraid of them. Children were kidnapped and indoctrinated. Now, these children live in mainstream society. The victims of Isis are afraid of these children.
Salafi
This form of Islam is Sunni. It was created in Egypt during the 1800's. It was a reaction to European conquest. Muslims that follow this form of Islam believe they should behave like Muslims did during the time of the prophet. There are 3 types of people that follow this. Purists don't get involved in politics. Activists are political. Jihadists want to topple the government. Salafism has similarities to Wahhabism.
They have killed over 2,000 people in 31 countries.
Asia: Women were raped and put in sex slavery in Syria and Iraq. Isis killed several soldiers in Yemen @ a military base. 25 soldiers were killed in Benghazi. Isis attacked a police station in the capital of Saudi Arabia. No one was harmed. A police officer was assassinated in Riyadh by Isis. Supporters of Isis suicide bombed a military base in Yemen killing 30 police officers. There were many more attacks but this will suffice.
Isis sells oil and electricity. They may be producing over 20,000 barrels of oil a day. They extort $ from humanitarian workers. They have a lot of military weapons, which they sell to other terrorists. They tax business and individuals. They received a lot of $ when they took over a bank in Mosul. They sell artifacts and traffic drugs. Darkweb is used by Isis to get donations.
Isis Supporters
Isis has been supported by the U.S., Turkey, Saudi Arabia, Israel, Gulf States, etc. Some of the weapons Isis uses come from the U.S. and Saudi Arabia. Isreal provides air support for Isis. Turkey is supporting Isis because they are @ war with the Kurds. Gulf States help fund Isis.
Conclusion
Isis comes from Al Qaeda in Iraq. They want 2 create a caliphate. They follow a very conservative form of Islam called Salafi. They have killed more than 2,000 people in 3 continents. They have various ways making $. They are supported and opposed by different nations and organizations.
https://en.wikipedia.org/wiki/Islamic_State_of_Iraq_and_the_Levant#Foundation_(1999–2006)
https://www.vox.com/cards/things-about-isis-you-need-to-know
https://www.cnn.com/2015/12/17/world/mapping-isis-attacks-around-the-world/index.html
https://www.nbcnews.com/feature/101/video/where-does-isis-get-its-money-569419843934
https://en.wikipedia.org/wiki/Finances_of_ISIL
https://www.nytimes.com/2018/01/31/opinion/editorials/us-allies-isis-turkey.html
Israeli Support of Isis
http://www.newsweek.com/us-actually-agrees-iran-syria-says-turkey-helping-isis-attacking-afrin-852159
http://www.bbc.com/news/world-middle-east-29004253