What has the territorial defeat accomplished?
Islamic State's possession of land in Iraq and Syria set it apart from other like-minded groups such as al-Qaida and became central to its mission when it declared a caliphate in 2014, claiming sovereignty over all Muslim lands and peoples.
Destroying the quasi-state it built there denies the group its most potent propaganda and recruiting tool as well as a logistical base from which to train fighters and plan coordinated attacks overseas.
It also freed its former subjects from summary executions and draconian punishment for breaking its strict laws or, for some minorities, sexual slavery and slaughter.
Warfare wiped out thousands of its fighters. And, financially, its defeat deprives it of greater resources than any modern jihadist movement has enjoyed, including taxes on its inhabitants and the proceeds of oil sales.
What threat does Islamic State still pose in Iraq and Syria?
In its previous guise as an al-Qaida offshoot in Iraq a decade ago, it navigated adversity by going underground, biding its time to rise suddenly again.
Since suffering devastating territorial losses in 2017, ISIS has steadily turned again to such tactics. Sleeper cells in Iraq have staged a scatter-gun campaign of kidnappings and killings to undermine the Baghdad government.
The group has also carried out many bombings in northeast Syria, which is controlled by U.S.-backed Kurdish forces, including one that killed four Americans in January. Kurdish and U.S. officials say its threat there persists.
In Syria, its fighters still hold out in the remote desert area near the road from Damascus to Deir al-Zor.
What has happened to its leaders, fighters and followers?
The fate of its leader, Abu Bakr al-Baghdadi, remains a mystery. The U.S. government's top experts strongly believe he is alive and possibly hiding in Iraq, U.S. sources recently said. Other top-echelon leaders have been killed in air strikes.
Thousands of its fighters and civilian followers have also been killed and thousands more captured. An unknown number remain at large in both Syria and Iraq.
Iraq is putting on trial, imprisoning and often executing Islamic State detainees. The U.S.-backed Syrian Democratic Forces (SDF) holds around 800 foreign fighters. More than 2,000 Islamic State wives and children are in its hands too. Many low-level local operatives have been released in Syria.
The SDF complains that Western states are reluctant to take back the foreign fighters, who are widely seen as a security threat at home but who might be hard to legally prosecute.
Can it still organize or inspire attacks overseas?
As Islamic State clung to its last scrap of land, the head of Britain's spy agency MI6 warned that the group would return to "asymmetric" attacks.
Even after it began losing ground militarily, the group still claimed responsibility for attacks made in different countries, though often these have been blamed on "lone wolves" without its direction.
It started years ago to call on followers abroad to plan their own attacks, rather than focusing purely on ones staged by trained operatives supported by the group's hierarchy.
In early 2018, the head of U.S. military central command said Islamic State was resilient and remained capable of "inspiring attacks throughout the region and outside of the Middle East."
What does its fall mean for the future of global jihad?
Although Islamic State's core territory was in Iraq and Syria, jihadists fighting in other countries, notably Nigeria, Yemen and Afghanistan, pledged their allegiance to it.
Whether those groups will still wear its mantle, especially if Baghdadi is captured or killed, is an open question, but there seems little chance they will soon end their campaigns.
Al-Qaida also retains numerous franchises around the world and other militant Islamist groups operate in countries where normal governance has broken down.
Jihadist ideology has long proven itself able to mutate as circumstances change, and there is no shortage of warfare, injustice, oppression, poverty, sectarianism and naked religious hatred for it to exploit.
