So, what is gray matter?
In the brain, there is both white and gray matter. It has to do with how a nerve cell is shaped. The brain cell has a main part of its “body”, called the cell body, which does most of the things it needs to stay alive. For example, it's in the cell body where neurons deal with waste, energy production, and the making of proteins. The white matter is a long extension from this cell body. These long structures have the main purpose of transmitting faster signals to the next nerve cell. Gray matter is where most of the cell bodies live, and the white matter is a collection of long extensions that transmit faster signals.