A baby is a human infant aged under 12 months and below.During the first three months, babies are often asleep. They also learn to open and shut his/her hands, raise the head, stretch the legs and recognize familiar things and people. From the 4th to 7th months, babies are more active. They try to feed themselves, roll side to side, tries to crawl and responds to sounds. From the 8th to 12th month, babies can move their arms and legs, take first steps, communicate through facial expressions and imitate gestures.