WCAG's contrast requirements ensure that text is legible to all users, including those with visual impairments or color vision difficulties. WCAG 2.1 specifies different contrast ratios: normal text requires at least 4. 5:1 contrast against the background, while large text (18pt+ or 14pt+ bold) requires at least 3:1. For AAA level (the highest standard), the requirements are 7:1 and 4. 5:1. Contrast is measured between the brightest and darkest colors and can be tested with tools such as WebAIM's contrast checker or built-in browser developer tools. Contrast requirements also apply to graphic elements such as icons and buttons that convey information. Important to note is that color should never be the only way to convey information - always combine with other visual cues such as text, icons or patterns. Good contrast benefits all users, not just people with visual impairments, especially in different lighting conditions such as outdoors or on mobile devices.
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