Color blindness
Color blindness is a class of visual conditions in which the perception of certain colors is impaired or absent. The most common form, red-green color blindness, affects roughly 8% of men and 0.5% of women of Northern European descent.
Detailed explanation
The most common types are protanopia (red weakness), deuteranopia (green weakness), and tritanopia (blue weakness). Less common is achromatopsia (total color blindness, perceiving only greyscale). Color blindness is genetic in most cases and present from birth.
WCAG 2.1 SC 1.4.1 (Use of Color) at Level A requires that color is not the only means of conveying information — error states, required-field indicators, and chart series must have a non-color cue (icon, text label, pattern). SC 1.4.3 (Contrast Minimum) at AA requires sufficient luminance contrast which also helps low-vision users regardless of color perception.
How this applies to Shopify stores
Shopify storefronts commonly fail 1.4.1 with color-only inventory indicators (red dot = out of stock, green dot = in stock) or color-swatch product variants without text labels. AccessComply detects color-only signaling and flags it.
Primary source: w3.org