It is built on an ideology of sectarianism, antisemitism, anti-Zionism and anti-Americanism; promotes intolerant and conservative strands of religious practice; viciously represses dissent through horrific public violence and covert surveillance; levies arbitrary taxes that effectively amount to a protection racket; spends finances raised from the sale of oil and similar resources to finance its military machine; and cleverly plays on tribal or other divisions to co-opt local powerbrokers.
The question is what can be done about it - and its affiliates and those of Al-Qaeda around the region and the world.
Here again, states have the primary role. The current problem is that all the states of the Middle East, and powers beyond, have their own agendas.
Turkey will not allow the one force capable of really taking on Daesh - the Kurds - to do so. Tehran and Moscow back the Assad regime, while the US and France see the removal of the dictator, who has killed many more of his own countrymen than Islamic militants have, as a prerequisite to effectively dealing with Daesh. Iraq has its own aims and problems, with Baghdad still very close to Tehran despite the departure of Nouri al-Maliki, the sectarian former prime minister. The Saudis are more worried about Iran's Shia expansionism and are preoccupied with the proxy war against their regional rivals in Yemen than anything happening in Syria. And so on. Compounding the problem is a lack of governance at an international, even global, level.
Sensitive to domestic concerns, President Barack Obama has chosen to follow a policy in the Middle East which could, as regards Syria at least, be described charitably as minimalist. The United Nations has been hamstrung by divisions on the Security Council.
If it looks as if no one is taking charge, that is because no one is.
The Paris attacks, as well as the ongoing refugee crisis, may change this. The sheer horror of the scenes from the French capital, as well as the indiscriminate nature of the killing, should focus policymakers' minds not just on the problem of Daesh but the broader issue of Islamic militancy. Some kind of diplomatic compromise that would align the currently diverging forces against Daesh is not impossible if enough powers make enough concessions.
Is there a military option? A major "boots on the ground" operation involving tens of thousands of US troops would probably defeat Daesh with relative ease but then have to do something with the invaded territory. The scattered supporters of Daesh would be a major threat. More air strikes, better guided by more special forces on the ground, will help.
A final problem is the status of Al-Qaeda in Syria and its affiliate, Jabhat al'Nusra (Jan). The group pointedly refused to join other Syrian opposition groups in condemning the Paris attacks, as one would expect.
But Jan have pursued a more sophisticated strategy than the brutal Daesh, avoiding foreign operations and concentrating, with some success, on building a solid support base in Syria. It would make little sense to eliminate Daesh because of its global threat and leave the group set up by those responsible for 9/11 and so many other attacks in place.
Western powers, including the UK, say that if the loathsome Assad, from a Shia heterodox sect, is removed, the raison d'etre of the violent Islamic militant groups, whose local fighters are drawn from the Sunni majority in Syria, will disappear and they will be fundamentally weakened.
The Russians and others, who back Assad, say that only by restoring the authority of the regime can Daesh and Jan and others be destroyed.
In the end, it is states that are the problem and, undoubtedly, the answer too.
