Child Development Stages are the different stages of growth and learning that a child goes through as they grow up. It is like a stairway. As your child gets older, each step gets higher and higher until they reach the top. Each stage has different milestones that a child should reach in order to start the next stage. For example, when your child is just learning to walk, this is the first stage they go through. Then they might learn to say a few words, or start expressing their feelings, or learn to be more independent. All of these changes happen as your child grows.