The brain (or encephalon) is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. The brain is the largest cluster of neurons in the body and is typically located in the head, usually near organs for special senses such as vision, hearing and olfaction. It is the most specialized and energy-consuming organ in the body, responsible for complex sensory perception, motor control, endocrine regulation and the development of intelligence. Wikipedia (CC BY-SA 3.0)