In 2003, some people in power thought that Iraq had dangerous weapons that could hurt a lot of people. They told other people that the only way to keep everyone safe was to go to war with Iraq and make sure they didn't have those weapons anymore.
So, a group of soldiers from America and some of their friends from other countries went to Iraq and started fighting against the Iraqis who were guarding the weapons. It was like a giant game of tag, but with guns.
After a little while, they found out that Iraq didn't actually have those dangerous weapons. But, instead of leaving Iraq, they decided to stay and try to make things better there. They tried to help the people in Iraq and make it a safer place for everyone.
The war lasted for a few years and many people on both sides got hurt or died. Eventually, the soldiers from America and their friends were able to leave Iraq and things started going back to normal there, although it was never quite the same again.