The Iraqi insurgency denotes groups using armed resistance against the US-led Coalition that is currently in Iraq. These groups may also oppose the newly created Iraqi government. The fighting appears both as a resistance to the USA led coalition as well as a civil war in Iraq among the diverse groups in the population. The insurgents are involved in asymmetric warfare and a war of attrition. The period of the insurgency has seen numerous human rights violations by both insurgent groups and Coalition forces.

The insurgency began shortly after the 2003 Coalition invasion of Iraq and before the establishment of a new Iraqi government. From at least 2004, and as of May 2007, the insurgency has primarily targeted Coalition armies and, latterly, Iraqi security forces seen as collaborators with whom they consider the enemy. During this period, only 10% of significant attacks have targeted Iraqi civilians (see Tactics of the Iraqi insurgency). Many militant attacks have been directed at the police and military forces of the new Iraqi government. They have continued during the transitional reconstruction of Iraq, as the new Iraqi government tries to establish itself. As in most guerrilla warfare, civilians on all sides bear the brunt of the violence. According to a February-March 2007 poll, 51% of the Iraqi population approve of the attacks on Coalition forces. When broken down along sectarian lines, over 90% of the Arab Sunni, many of whom held power under President Saddam Hussein, approve of the attacks.

Iraq's deep sectarian divides have been a major dynamic in the insurgency, with support for the insurgents varying amongst different segments of the population.