Maroon (#800000) is a dark, highly saturated red hue. Maroon is a dark brownish red; the word comes from the French marron, meaning chestnut.
In RGB it is made of 128 red, 0 green and 0 blue. Its HSL hue angle is 0° with 100% saturation and 25% lightness, while its perceptual OKLCH lightness is 38% with a chroma of 0.155. For print, a starting CMYK mix is 0% cyan, 100% magenta, 100% yellow and 50% black.
As a text color on white, Maroon has a contrast ratio of 10.95:1, which passes WCAG AA for normal text. On black it reaches 1.92:1 and fails AA. If you use Maroon as a background, put white text on it. The APCA lightness contrast is Lc 11 for black text and Lc -97 for white text.
Its perceptual complement is #004B54, close to charcoal. Colors that look most similar are burgundy, wine, chocolate. People with red-green color blindness see maroon quite differently (ΔE 15), so do not rely on it alone to signal meaning.