Making sense of the brain's mind-boggling complexity isn't easy. What we do know is that it's the organ that makes us human, giving people the capacity for art, language, moral judgments, and rational thought. It's also responsible for each individual's personality, memories, movements, and how we sense the world.
All this comes from a jellylike mass of fat and protein weighing about 3 pounds (1.4 kilograms). It is, nevertheless, one of the body's biggest organs, consisting of some 100 billion nerve cells that not only put together thoughts and highly coordinated physical actions but regulate our unconscious body processes, such as digestion and breathing.
read more in science.nationalgeographic.com