The fontanel is a gap in the skull formed by the poorly bonded bones of the infant’s skull and is divided into anterior and posterior fontanelles. The posterior fontanel is near the occipital part of the head and is a triangular gap formed by the bone gap between the parietal and occipital bones on both sides, which is usually very small or already closed in infants after birth, and closes no later than 6-8 weeks. Anterior fontanel, at the top of the head, is a diamond-shaped gap formed by the bony suture between the frontal bone on each side and the parietal bone on each side, and most close between the ages of one and one and a half years, no later than two years of age. Early or delayed closure of the fontanel is a sign that there is something wrong with the child’s body, which requires parents to pay close attention to and take the child to the hospital for timely and appropriate treatment.