Okay kiddo, have you heard about something called war? It's a very big fight between different countries or groups of people. Now, think about when you play with your friends and you agree on rules before starting the game, right?
Well, countries that go to war also agree on some rules before starting the fight. These rules are called International Humanitarian Law, or sometimes people call it the Laws of War.
These rules are important because they try to protect the people who are not fighting in the war, like the children, the women, the elderly, and the sick. Now, sometimes during war, some people break these rules and that is what we call a war crime.
For example, let's say that you are playing hide-and-seek with your friends and one of them decides to cheat and hide in a place where it's forbidden. That would be breaking the rules of the game, right? The same thing happens during war when someone, for example, attacks hospitals or uses weapons that can hurt a lot of innocent people.
When someone commits a war crime, they can be punished by an international court, just like you can be punished by your parents for breaking the rules at home. We want everyone to follow the rules to make sure that war is as safe as possible for everyone caught up in it.