Gray is made by mixing black and white. While black and white are technically not colors – black is a shade, while white is a tint – mixing the two in equal amounts yields a medium gray. No two pure colors can be mixed to make gray.
Black is the complete absence of color, while white is made by combining the colors of the visible portion of the electromagnetic spectrum – red, orange, yellow, green, blue, indigo and violet – in equal parts. Adding more white than black to the mix yields a gray that is lighter than medium gray. Adding more black than white yields a gray that is darker than medium gray. Medium gray is the neutral used to set the dark and light points in art and digital imaging.