Paediatrics is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. 
Paediatrics is different from adult medicine in more ways than one. The smaller body of an infant, neonate, or child is different physiologically from that of an adult.
A paediatrician is a physician who provides not only medical care for children who are acutely or chronically ill but also preventive health services for healthy children. A paediatrician manages the physical, mental, and emotional well-being of the children under their care at every stage of development, in both sickness and health.
It also encompasses the preventive medicine by administration and monitoring the immunisation from birth to young adulthood.