How do world leaders get charged with War Crimes? What’s the ICC?

We all throw out terms like “war crimes”. But what are the actually legal repercussions for committing one, or the mechanisms behind them? That’s where the ICC comes in. Also often referred to as “The Hague”. I don’t like my color grading on this one. And sorry, I didn’t feel like changing my shirt twice. I was sleepy eepy.