Gray & White Matter
The brain has 2 primary cell types, commonly characterized by their color. The color designation derives from appearance of a brain preserved in formaldehyde. In a working brain, white matter is pinkish white, while gray matter is pinkish tan. The pink hue comes from blood capillaries.
The outside of the brain is largely coated in nerve cells: gray matter. Inside are glia cells: white matter. Overall, glia cells predominate in the brain, both in brain mass and in processing control.