Children come into the world knowing precious little. They learn almost incidentally by observing the happenings around them and manipulating their surroundings through touch, sound, facial expression and movement. We set physical limits to keep our exploring munchkins from danger. As they grow in size and ability, though, physical limits are inadequate for the sea of behaviors they'll experiment with. It's our job as parents to let our kids know which behaviors are acceptable and which aren't. These limits are essential for safety and household harmony, but they also help children feel secure by showing that you care and that you want to keep them safe. Limits also help your child develop a sense of responsibility for his or her actions.