If one part of the child is not developed, the child does not grow into a healthy, happy adult. He or she is not complete. Physical development is the way a child's body grows. It is normal for children to grow at different rates. For example, some might walk at 11 months and some might walk at 16 months.
Intellectual development involves a child's thinking.
Children learn to think by undertaking challenging tasks. Reasoning their way through different tasks helps children learn. Emotional growth involves the development of a child's feelings. A child learns what it feels like to be sad, angry, hurt, confident, excited and happy. Social development is the way a child learns to work, play and interact with other people.