See below for a brief description for the sources used in this guide.
THE BROOKINGS INSTITUTION
The Brookings Institution pulls together information on Iraq from a variety of sources to compile an Iraq Index which is regularly updated. The institution, based in the US, conducts independent research into public policy issues.
INTERNATIONAL ORGANIZATION FOR MIGRATION
The IOM works inside Iraq monitoring the numbers of newly-displaced people. It is an independent organisation that works alongside the Iraqi government's Ministry of Displacement and Migration.
IRAQ BODY COUNT
Iraq Body Count is an independent website set up to record the number of civilians and police killed in the Iraqi conflict.
All those deaths caused by the coalition, the insurgency, or by the breakdown of law and order that followed the 2003 invasion of Iraq are added to the total.
IBC's methodology requires two separate media reports before any fatalities can be included.
Occasionally different media organisations give different casualty figures for the same incident. IBC resolves this problem by keeping two tallies, one for a minimum number of deaths, and one for a maximum.
IRAQ COALITION CASUALTY COUNT
Like IBQ the Iraq Coalition Casualty Count is an online database. As its name suggests it lists military casualties from coalition countries.
The site uses statements from the US Defense Department, and the British Ministry of Defence as its main sources, although it does use reports attributed to them by other media outlets.
THE IRAQI GOVERNMENT
The Iraqi Health Ministry
has released its own figures on the casualty rate in the Iraqi conflict.
They are an estimated total based on the number of bodies brought to mortuaries and hospitals in recent months. Those figures have then been used to create an estimate for the total period of the three-and-a-half year conflict.
The high death toll published in the medical journal, the Lancet in October this year, has attracted a great deal of controversy. This is hardly surprising as at 655,000 it is by far and away the largest estimate of the number of deaths in Iraq.
The figure was reached at after researchers conducted interviews with 1,849 Iraqi households from 47 sites across the country.
The responses gathered were used to calculate an average mortality rate. This figure was used in turn to estimate the total number of deaths caused, both directly and indirectly, by violence since 2003.
The UK Ministry of Defence keeps up to date details of UK military fatalities on its website, as well as maps and information on which UK units are in Iraq.
US DEPARTMENT OF DEFENSE
The US Defense Department keeps US military casualty figures on its website for those killed in Operation Iraqi Freedom. Details of the number of wounded in action are also available.
UNITED NATIONS REFUGEE AGENCY
The UNHCR is among the humanitarian agencies working with the hundreds of thousands of displaced families in Iraq. It produces briefing reports and detailed maps of the region, which include details of refugee camps, settlements and UNHCR offices.