The part of the CENTRAL NERVOUS SYSTEM contained within the skull. It is the most complex and least understood part of the human body. Because of the brain's organising role in all human BEHAVIOUR, it is sometimes compared to a central computer which stores, retrieves and utilises information. However, the brain is infinitely more complex and powerful than that. In an important sense, our brain is what makes us human. All the limitless forms of human behaviour are a direct result of the brain's capacity.