A skeleton is the hard structure that protects the internal organs of a living thing. Skeletons can be inside the body or outside the body. In mammals, which include humans, the skeleton is made of bones. All the bones, when they are joined together, make the "skeletal system" of a body. The skeletal system or "skeleton" is under the skin, the muscle and the tissue of the body. The skeleton supports the skin, muscle and tissue, and all the organs that are inside the body. The skeleton protects important internal organs like the brain, heart and lungs. If humans did not have a skeleton then the body would be flat as the skeleton gives the body its frame.

The important parts of a human body are the head, the spine, the chest, the abdomen, the arms and hands, and the legs and feet.

The head bones all together are called the skull.

The spine supports the head, the chest and the structure that carries the arms. It is made of small bones called vertebrae. The spine, all together, is called the spinal column. It is not straight, but has curves that help to support the body, and help the person to move and bend. One bone is a "vertebra". More than one are "vertebrae".
The "vertebrae" have different names, depending on the part of the body they are joined to.

This part of the body is made of the sacrum and the two pelvic bones which are joined to it on either side. The pelvic bones are carried by the leg bones, and they support the "spinal column". Each pelvic bone has a strong structure for the leg bone to fit into, so that a person can stand, walk, run and jump. Each pelvic bone spreads into a large flat plate which supports the person's "internal organs". The pelvis of a woman spreads into a wider shape than a man's, so that when the woman is pregnant, the baby is supported by the pelvis, until it is ready to be born. At the bottom of the pelvis is a large opening, big enough for a baby to pass through.

The chest is called the thorax, and the vertebrae that are part of it are the thoracic vertebrae. The thorax is made up of long flat curved bones called ribs. At the back, the ribs are joined to the vertebrae. At the front, most of the ribs are joined to the sternum, which is often called the "breast bone". All together, the "thorax" protects the heart, lungs and stomach.

At the top of the "thorax" is the shoulder girdle. This is made of two thin horizontal bones at the front, joined to the "sternum". These two bones are called the clavicles or "collar bones". At the back of the "thorax" are two flat triangular-shaped bones called the scapulae, or "shoulder blades". The "clavicles" and "scapulae" come together on each side to make "shoulders". The bones of the arms fit into sockets (cup-like holes) in the "scapulae".

Arms and legs both have a thicker bone at the top and two thinner bones at the bottom. They both have a rotating joint at the top, and a hinge joint in the middle. The hands and feet have lots of bones and are joined to the arms and legs by small bones with sliding parts.

A skeleton, or just a skull, has often been used as a symbol for Death.

Skeletons, particularly living skeletons, have often been used in horror stories and comedies.