What is skeleton ?

In biology, the skeleton or skeletal system is a strong framework that supports the body. External rigid frameworks, such as those found in some invertebrates (e.g. insects), are termed exoskeletons. Internal rigid frameworks, such as those found in most vertebrates (e.g. mammals), are termed endoskeletons.

The average adult human skeleton has around 206 bones These bones meet at joints, the majority of which are freely movable, making the skeleton flexible and mobile. The skeleton also contains cartilage for elasticity. Ligaments are strong strips of fibrous connective tissue that hold bones together at joints, thereby stabilizing the skeleton during movement.

Skeleton (anatomy), term applied to all the rigid or semirigid structures supporting the soft tissues of an animal's body and providing leverage for muscular action. In vertebrates, the skeleton is known as the endoskeleton and is formed within the body. Some invertebrate animals, such as insects and crustaceans, have skeletons known as exoskeletons on the outside of the body.
source: wiki/encarta encyclopedia