(CNN) Here's a look at Islamic State in Iraq and Syria (ISIS) .

Facts

Started as an al Qaeda splinter group.

ISIS aims to create an Islamic state called a caliphate across Iraq Syria and beyond.

The group implements Sharia Law, rooted in eighth-century Islam, to establish a society that mirrors the region's ancient past.

ISIS is known for killing dozens of people at a time and carrying out public executions, crucifixions and other acts.

ISIS uses modern tools like social media to promote reactionary politics and religious fundamentalism. Fighters are destroying holy sites and valuable antiquities even as their leaders propagate a return to the early days of Islam.

In 2015, ISIS was believed to be holding 3,500 people as slaves, according to a United Nations report. Most of the enslaved were women and children from the Yazidi community, but some were from other ethnic and religious minority communities.

ISIS's revenue comes from oil production and smuggling, taxes, ransoms from kidnappings, selling stolen artifacts, extortion and controlling crops.

Leader

Abu Bakr al-Baghdadi was the leader of ISIS from April 2010 until his death in October 2019. After his death, ISIS announced its new leader would be Abu Ibrahim al-Hashimi al-Qurashi.

Baghdadi was detained for several months in Camp Bucca, which was a US-run prison in southern Iraq. He was released in 2004.

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Timeline

2004 - establishes al Qaeda in Iraq (AQI). Abu Musab al-Zarqawi establishes al Qaeda in Iraq (AQI).

2006 - Under Zarqawi, Under Zarqawi, al Qaeda in Iraq tries to spark a sectarian war against the majority Shia community.

June 7, 2006 - Zarqawi is killed in a US strike. Abu Ayyub al-Masri takes his place as leader of AQI.

October 2006 - Masri announces the creation of Islamic State of Iraq (ISI), and establishes Abu Omar al-Baghdadi as its leader.

April 2010 - Abu Bakr al-Baghdadi becomes leader of ISI after Abu Omar al-Baghdadi and Masri are killed in a joint US-Iraqi operation.

April 2013 - ISI declares its absorption of an al Qaeda-backed militant group in Syria, Jabhat al-Nusra, also known as the al-Nusra Front. Baghdadi says that his group will now be known as Islamic State in Iraq and the Levant (ISIL or ISIS).

January 2014 - ISIS takes control of Falluja.

February 3, 2014 - Al Qaeda renounces ties to ISIS after months of infighting between al-Nusra Front and ISIS.

May 2014 - , forcing them to take lessons in radical Islamic theology, according to London-based monitoring group Syrian Observatory for Human Rights. ISIS kidnaps more than 140 Kurdish schoolboys in Syria , forcing them to take lessons in radical Islamic theology, according to London-based monitoring group Syrian Observatory for Human Rights.

June 9-11, 2014 - ISIS takes control of Mosul and Tikrit.

June 20, 2014 - The UN announces that The UN announces that more than one million Iraqis have been displaced

June 28, 2014 - Iraqi Iraqi Kurdistan restricts border crossings into the region for refugees.

June 30, 2014 - , bringing the total US forces in Iraq to nearly 800. Troops and military advisers are sent to Iraq to support Iraqi security forces and help protect the US Embassy and the airport in Baghdad. The Pentagon announces the United States is sending an additional 300 troops to Iraq , bringing the total US forces in Iraq to nearly 800. Troops and military advisers are sent to Iraq to support Iraqi security forces and help protect the US Embassy and the airport in Baghdad.

July 2014 - ISIS takes control of Syria's largest oilfield and seizes a gas field in the Homs Province, storming the facility and killing dozens of workers. ISIS takes control of Syria's largest oilfield and seizes a gas field in the Homs Province, storming the facility and killing dozens of workers. Militants conquer a 90-mile stretch of Syrian towns , from Deir Ezzor to the Iraq border. In Mosul, they blow up Jonah's tomb , a holy site dating back to the 8th century BC.

August 6, 2014 - , home of a religious minority group called the Yazidis. More than 30,000 Yazidi families are stranded in the Sinjar Mountains. A Yazidi lawmaker says that 500 men have been killed, 70 children have died of thirst and women are being sold into slavery. ISIS fighters attack the northern Iraqi town of Sinjar , home of a religious minority group called the Yazidis. More than 30,000 Yazidi families are stranded in the Sinjar Mountains. A Yazidi lawmaker says that 500 men have been killed, 70 children have died of thirst and women are being sold into slavery.

September 2, 2014 - ISIS releases a video showing the beheading of ISIS releases a video showing the beheading of US journalist Steven Sotloff. The apparent executioner speaks in the same British accent as the man who purportedly killed Foley.

September 11, 2014 - The CIA announces that the number of The CIA announces that the number of ISIS fighters may be more than three times the previous estimates.

September 13, 2014 - ISIS posts a video showing the apparent execution of British aid worker David Haines.

September 23, 2014 - The United States carries out airstrikes against ISIS.

November 14, 2014 - The UN Independent International Commission of Inquiry on Syria concludes that ISIS has committed war crimes and crimes against humanity.

February 3, 2015 - Video and still images posted by ISIS apparently shows Video and still images posted by ISIS apparently shows Jordanian pilot Moath al-Kasasbeh being burned alive while locked in a cage.

February 10, 2015 - , after receiving confirmation from ISIS, including a photo of her wrapped in a burial shroud. Mueller's family announces she is dead , after receiving confirmation from ISIS, including a photo of her wrapped in a burial shroud.

February 11, 2015 - Obama asks the US Congress to formally Obama asks the US Congress to formally authorize use of military force against ISIS

February 22, 2015 - ISIS releases a video that appears to show at least ISIS releases a video that appears to show at least 21 Kurdish Peshmerga fighters in cages carried down Iraqi streets

February 26, 2015 - Jihadi John, the disguised man with a British accent who appeared in ISIS videos as the executioner of Western hostages, is identified as Jihadi John, the disguised man with a British accent who appeared in ISIS videos as the executioner of Western hostages, is identified as Mohammed Emwazi, a Kuwaiti-born Londoner . On the same day, ISIS releases a video of its fighters destroying antiquities at the Mosul Museum

March 2015 - ISIS posts images of ISIS posts images of a man being thrown off a building in Raqqa, Syria . He had been accused of being gay. There are at least a half dozen documented cases of ISIS killing men accused of being gay.

March 1, 2015 - All but one are reportedly from a group of 220 Assyrians captured in northern Syria. ISIS releases 19 Christian prisoners. All but one are reportedly from a group of 220 Assyrians captured in northern Syria.

March 12, 2015 - Iraqi forces retake most of Tikrit. In western Iraq, ISIS blows up the Iraqi army headquarters north of Ramadi, killing at least 40 Iraqi soldiers.

April 8, 2015 - According to Iraqi Kurdistan officials, According to Iraqi Kurdistan officials, ISIS releases more than 200 Yazidi women and children, as well as the ill or elderly.

May 17, 2015 - of Ramadi, the largest city in western Iraq, after government security forces pull out of a military base. ISIS seizes control of Ramadi, the largest city in western Iraq, after government security forces pull out of a military base.

June 14, 2015 - is reportedly one of four ISIS suicide bombers who attack the headquarters of a Shia militia group in Iraq, A British teen, Talha Asmal, is reportedly one of four ISIS suicide bombers who attack the headquarters of a Shia militia group in Iraq, killing at least 11 . Before the bombing, ISIS posted photos of Asmal, 17, posing next to their black flag on social media. According to the BBC, Asmal left England in March to join the Islamic fundamentalists.

June 19, 2015 - The US State Department issues its annual terrorism report, declaring that ISIS is becoming a greater threat than al Qaeda. The The US State Department issues its annual terrorism report, declaring that ISIS is becoming a greater threat than al Qaeda. The frequency and savagery of ISIS attacks are alarming, according to the report.

June 24, 2015 - that ISIS militants have destroyed two Muslim holy sites in Palmyra. The group attacked a 500-year-old shrine and a tomb where a descendent of the Prophet Mohammed's cousin was reportedly buried. The Syrian government reports that ISIS militants have destroyed two Muslim holy sites in Palmyra. The group attacked a 500-year-old shrine and a tomb where a descendent of the Prophet Mohammed's cousin was reportedly buried.

July 4, 2015 - The Syrian Observatory for Human Rights reports it has received a video showing The Syrian Observatory for Human Rights reports it has received a video showing ISIS militants executing 25 captives in Palmyra.

November 12, 2015 - , killing more than 40 people and wounding hundreds. ISIS claims responsibility for the attack. Two suicide bombs hit the Bourj al-Barajneh district of southern Beirut , killing more than 40 people and wounding hundreds. ISIS claims responsibility for the attack.

December 10, 2015 - A spokesman for the US-led coalition confirms that A spokesman for the US-led coalition confirms that ISIS Finance Minister Abu Saleh was killed in an airstrike in late November in Iraq.

December 28, 2015 - from ISIS and raise the Iraqi flag on top of the government compound in the city's center, according to an Iraqi military spokesman. Iraqi troops retake the city of Ramadi from ISIS and raise the Iraqi flag on top of the government compound in the city's center, according to an Iraqi military spokesman.

January 24, 2016 - ISIS releases a video that purports to show final messages from the Paris attackers.

March 22, 2016 - kill more than 30 people and wound about 270 more. ISIS claims its "fighters" launched the attacks. Attacks on the airport and a subway station in Brussels, Belgium, kill more than 30 people and wound about 270 more. ISIS claims its "fighters" launched the attacks.

March 25, 2016 - A US official tells CNN that special operations forces intended to capture Qaduli alive but the plan was modified at the last moment. The Pentagon confirms that US forces have killed ISIS' finance minister, Abd al-Rahman Mustafa al-Qaduli. A US official tells CNN that special operations forces intended to capture Qaduli alive but the plan was modified at the last moment.

June 28, 2016 - when three attackers arrive at Turkey's Istanbul Ataturk Airport in a taxi, then open fire before blowing themselves up. US officials believe the man who directed the three attackers is Akhmed Chatayev, a terrorist from Russia's North Caucasus region and a well-known ISIS lieutenant. At least 44 people die and more than 230 are injured when three attackers arrive at Turkey's Istanbul Ataturk Airport in a taxi, then open fire before blowing themselves up. US officials believe the man who directed the three attackers is Akhmed Chatayev, a terrorist from Russia's North Caucasus region and a well-known ISIS lieutenant.

July 1-2, 2016 - Attackers invade the Holey Artisan Bakery cafe in a diplomatic enclave of Dhaka, the capital of Bangladesh. Attackers invade the Holey Artisan Bakery cafe in a diplomatic enclave of Dhaka, the capital of Bangladesh. Gunmen kill 20 hostages and two police officers before authorities raid the restaurant and end the nearly 11-hour standoff. ISIS claims responsibility for the attack, but Bangladeshi officials say the attack was carried out by homegrown militants. US officials focus on ISIS as the perpetrator after photos purportedly showing the inside of the cafe and dead hostages are posted on an ISIS-affiliated website.

September 16, 2016 - Pentagon Press Secretary Peter Cook says a Pentagon Press Secretary Peter Cook says a US air strike targeted and killed Wael Adel Salman , aka Abu Muhammad al-Furqan, ISIS's chief spokesman. Salman was the ISIS minister of information, responsible for overseeing the production of "terrorist propaganda videos showing torture and executions," Cook says.

October 24, 2016 - ISIS claims responsibility, releasing a photo of the three purported attackers but Pakistani military leaders say they believe a Pakistan-based group, Lashkar-e-Jhangvi carried out the attack. Suicide bombers attack sleeping cadets at a police training academy in Pakistan, killing 61 and injuring 117. ISIS claims responsibility, releasing a photo of the three purported attackers but Pakistani military leaders say they believe a Pakistan-based group, Lashkar-e-Jhangvi carried out the attack.

July 10, 2017 - Mosul is liberated from ISIS.

October 17, 2017 - . US-backed forces fighting in Raqqa say "major military operations" have ended, though there are still pockets of resistance in the city. ISIS loses control of its self-declared capital, the Syrian city of Raqqa . US-backed forces fighting in Raqqa say "major military operations" have ended, though there are still pockets of resistance in the city.

December 6, 2017 - Troop levels are trending down, according to the Pentagon, as Iraqi forces and the Syrian Democratic Forces have liberated about 97% of the territory and people in the caliphate declared by ISIS. The Pentagon announces that there are 5,200 American troops in Iraq and 2,000 troops in Syria. Troop levels are trending down, according to the Pentagon, as Iraqi forces and the Syrian Democratic Forces have liberated about 97% of the territory and people in the caliphate declared by ISIS.

July 25, 2018 - At least 166 people are killed in a suicide bombing and other attacks in the southern Syrian province of Suwayda, the UN Office for the Coordination of Humanitarian Affairs in Syria says. ISIS claims responsibility.

August 23, 2018 - ISIS releases what it says is an audio ISIS releases what it says is an audio message from Baghdadi . In the 55-minute recording, a man admits that ISIS groups are losing and urges his followers to carry on with the fight.

January 16, 2019 - A deadly A deadly explosion kills four Americans and at least 10 other people in the Syrian city of Manbij. ISIS claims responsibility for the attack.

April 2019 - For the first time in five years, ISIS releases what it says is a For the first time in five years, ISIS releases what it says is a new video message from Baghdadi

August 6, 2019 - The Pentagon issues a report saying that The Pentagon issues a report saying that ISIS is "re-surging" in Syria, less than five months after Trump declared the terror group's caliphate there had been 100% defeated. An accompanying message to the report, written by Glenn Fine, the principal deputy inspector general, notes that, "The reduction of US forces has decreased the support available for Syrian partner forces at a time when their forces need more training and equipping to respond to the ISIS resurgence."

August 21, 2019 - US Secretary of Defense Mark Esper states that US Secretary of Defense Mark Esper states that ISIS is not "in a resurgent state in Syria" despite the Pentagon report.

October 27, 2019 - Trump announces in a televised address at the White House that the Trump announces in a televised address at the White House that the "world's number one terrorist leader" is dead

October 31, 2019 - ISIS releases an audio message confirming the death of Baghdadi and announcing its new leader is Abu Ibrahim al-Hashimi al-Qurashi.

January 5, 2020 - The US led military coalition fighting ISIS announces that The US led military coalition fighting ISIS announces that it's temporarily stopping its counter ISIS missions in order to focus on protecting Iraqi bases and coalition forces from Iranian backed militias.

August 18, 2020 - The Trump administration informs the British government that The Trump administration informs the British government that it will not seek the death penalty for two high profile ISIS members known as "the Beatles" in an effort to convince the UK to provide critical evidence that can be used to prosecute the operatives in US courts.

September 2, 2020 - Omer Kuzu, a US citizen who had traveled to Syria to join ISIS and was captured, Omer Kuzu, a US citizen who had traveled to Syria to join ISIS and was captured, pleads guilty to supporting ISIS.