Gray matter is a kind of nerve tissue and an important part of the central nervous system. Gray matter is composed of neurons, glial cells and capillaries. The gray production of gray matter is related to the cell bodies and capillaries of neurons. Another important part of the central nervous system is white matter.

Gray matter is the place where a large number of neurons gather in the central nervous system. In typical gray matter, such as cerebral cortex, there are a large number of chemical synapses or electrical synapses between neurons as communication channels, forming an extremely complex neural circuit to realize a variety of sensory, motor or intermediate information processing. Therefore, gray matter is the place where the central nervous system deeply processes information. In contrast, white matter is composed of axons of neurons, so it has no function of processing information itself, only between different gray matter or gray matter.