The human skeleton is the frame inside our bodies. It has 206 bones in an adult. The skeleton has three important jobs. First, it gives our body its shape and support. Without bones, we cannot stand or sit. Second, it protects our soft organs. The skull is a bone that protects the brain. The ribs are bones that protect the heart and lungs. Third, the skeleton helps us move. Muscles connect to our bones. When muscles pull on the bones, we can walk, run, and lift things. Our bones are very strong, but they are also light. This system is very important for our daily lives.