Developmental milestones are guidelines for when a child typically develops certain skills in the various areas of development (cognitive, fine and gross motor, speech and language, and social-emotional). However, not all children develop those skills at the same exact age. For example, some children may learn to walk at 10 months while anotehr child doesn't start to walk until 12 months. That's ok. The child who is walking at 10 months may not have as many words as the child who learns to walk at 12 months. There is a range of development that is ok. However, when a child is obviously not meeting the developmental milestones in one particular area and this continues, parents should begin to questions why.