Hmm. What everyone else said is right, but something nobody told me is that when you're younger it can be irregular. Like skip a week you should have it. And when that happens usually the cramps are worse
It's different for everyone. These people are talking about all the pain and the blood. I, on the other hand, experience very little of that. I have cramps, but they are not painful enough to bother me, and there is barely any blood.