It is composed of cell bodies as opposed to white matter (cell axons). It has a gray brown color which comes from the capillary blood vessels and the neuronal cell bodies.
The function of gray matter is to route sensory or motor stimulus to interneurons of the CNS in order to create a response to the stimulus through chemical synapse activity. Gray matter structures (cortex, deep nuclei) process information originating in the sensory organs or in other gray matter regions. This information is conveyed via specialized nerve cell extensions (long axons), which form the bulk of the cerebral, cerebellar, and spinalwhite matter.