- Mosul: IS overran Iraq's second largest city on June 10, two weeks before declaring a "caliphate" in the swathes of territory it controls in Iraq and Syria.
Located 350 kilometres (217 miles) from Baghdad, and on the right bank of the Tigris river, it had about 1.5 million mainly-Sunni inhabitants prior to the IS offensive. The city has been all but emptied of its minorities.
Kurds backed by US warplanes have retaken Iraq's largest dam from the jihadists and have tightened the noose around Mosul, where US officials have expressed hopes the Iraqi army will launch an offensive soon.
- Tikrit: On June 11, IS seized the mainly Sunni-populated capital of Salaheddin province, 160 kilometres (100 miles) north of Baghdad on the road to Mosul.
On Monday, government forces pounded IS positions in and around Tikrit in the biggest offensive yet to retake the city involving around 30,000 troops and militia.
The city has symbolic importance because it was the birthplace of Salaheddin, the Muslim warlord of the same name who seized Jerusalem in 1187. It was the hometown of dictator Saddam Hussein, who was ousted in the 2003 US-led invasion before being executed.
- Tal Afar: The Shiite-majority town in the northern province of Nineveh and its airport fell into IS hands on June 23, after days of heavy fighting.
Some 380 kilometres (236 miles) north of Baghdad, it is strategically located between Mosul and the Syrian border.
Kurdish forces said in January 2014 they had managed to cut off the road linking Tal Afar and Mosul under a large-scale anti-IS offensive backed by the international coalition.
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- Fallujah: the restive city in the western province of Anbar fell out of government control even before a major IS push inside Iraq in June last year.
It was seized on January 2, 2014. The army has regularly bombarded the city, which is some 60 kilometres (37 miles) west of Baghdad, and has tried several ground operations in surrounding areas.
Fallujah is a symbol of the jihadist insurrection which inflicted heavy losses on occupying US forces between 2003 and 2006.
- Raqa: the de facto capital of IS, located less than 200 kilometres (124 miles) from the Iraqi border in the Euphrates valley. It counted 250,000 inhabitants before the start of the Syria conflict in 2011 and is the only provincial capital held by IS and the only one to escape the total control of the Damascus regime.
The jihadists, which impose their harsh interpretation of Islamic law, also currently controls most of the oil province of Deir Ezzor in the east, but government forces still hold the provincial capital.
IS has also taken several oil and gas fields in the province of Hasakeh in the northeast and near to Iraq and Turkey.
Since late 2014, IS has lost territory.
In Iraq, it lost the northern town of Baiji in November and then parts of the eastern province of Diyala in January. But on February 13 the jihadists took over large parts of Al-Baghdadi, putting it close to an airbase where US troops are training Iraqi forces.
In Syria, faced with Kurdish fighters backed by the international coalition, IS lost the battle for the northern town of Kobane, in its biggest setback since it surfaced in the civil war there in 2013.