Red is a primary color.
Red contains 100% red, 0% green, and 0% blue in RGB.
In CMYK, red contains 0% cyan, 100% magenta, 100% yellow, and 0% black.
Red is one of the safest web colors, listed as *F00*, which is shorthand for its hex code (#FF0000).
Here are some examples for using this color in CSS with Hex, RGB, HSL etc.