Writing, along with reading, makes up Literacy, one of the four specific areas of the Early Years Foundation Stage (EYFS). Learning to write is closely linked to a child's physical development. Before children can control the muscles in their hands, they need to develop their gross motor skills (those that need large or whole body movements). They also need to control their movements by developing their fine motor skills (precise, small muscle movements). By handling small objects, children are strengthening their hands and fingers, so that they can grip a pencil.
Before children are able to form letters, they need to learn how to make marks. By doing this they are working out how writing works, how to hold their pencil, what pressure to put on the paper and how to control the marks they make.