The document discusses normal physical development in young children. It states that children develop motor skills like crawling, walking, and running at different ages, and there is a wide range of ages that are considered normal. The "average ages" provided in parenting books should not be the only consideration - what matters most is whether a child meets milestones within the general time frame. Parents should provide opportunities for safe exploration and physical activity. Only if a child is significantly delayed in several skills compared to peers should a healthcare provider be consulted.