greyscale

A completely colorless, black-and-white image. The image is composed exclusively of shades of black, white, and grey. It is very common for comics and doujinshi to be in greyscale.

The image may have small highlights of color (known as spot colors), but the image as a whole should be predominately greyscale.

Don't use color tags like black eyes or black hair when tagging greyscale images. The exception is color background tags, so tagging white background, grey background, or black background is fine.

Guidelines

For completely colorless art, use greyscale.
For a post consisting of a single color that isn't grey, use monochrome, not greyscale.
For a mostly greyscale post with a small amount of color as a highlight, use greyscale and spot color.
For a post using a mix of color and greyscale, use partially colored, not greyscale.
For a colorless foreground and colorful background, use greyscale with colored background, not greyscale or partially colored.
For a post that has solid black shadings, use greyscale and high contrast.
For posts with a small variety of colors but more than two actual colors, use limited palette, not greyscale or monochrome.