Latching on is how the the baby fastens to the breast while breastfeeding. A good latch helps the baby get milk. This happens when the bottom of the areola (the area around the nipple) is in the baby's mouth. When the nipple is far back inside the baby's mouth this is a good latch. A latch that is not good happens when the baby does not have enough of the breast in his/her mouth. A shallow or short latch causes the nipple skin to press against the hard bones in the top of the baby's mouth. That will cause cracked nipples on the mother. Cracked nipples are painful and can bleed.