It is common for girls who have just started their periods to have no pain, for instance. Women who have had babies, too, often report that even though they used to get cramps, they no longer do. But most women experience at least a little discomfort during their periods sometime or another. Cramps tend to come with heavy bleeding, so they usually only last for the first day or two of your period, when there is the most bleeding. Sometimes they will begin before you start bleeding.
Cramps can be different in each woman.
They might be just tiny aches and twinges in her lower belly which are hardly noticeable. Or she might feel like a big hand is in her belly, squeezing hard. Or she might feel strange shooting pains that go up the insides of her thighs. Her lower back might hurt. Or she might just feel a certain kind of fullness inside - like a pressure that needs to be released.