Any tattoo can be completed in black and gray, but as a style in and of itself, there are two specific branches of black and gray.

1)Aside from not using color, the defining characteristics of biker or prison tats are that they often of a more morbid nature featuring skulls, or of a memorial nature. To this end, many, but not necessarily all biker/prison style tattoos feature sayings or phrases in script, and sometimes are nothing but script.

2)The other major branch of black and gray is known as fine-line, or in some circles, Chicano-style. The style originated in the Hispanic communities of East LA in the '70s. Arguably, this style is the evolution of the prison tattoo. It features fine lines with great depth of shading, all in tones of gray. Thanks to the warmth that the tones provide, this styles is often used for memorial pieces, and perhaps most effectively on portraits and other realistic pieces.