Font and text background colors must be chosen such that all text is clearly visible. For some examples of what not to do, see the examples below.
Some people cannot read text if there is not sufficient contrast between the text and background, for example, light gray text on a light background.
Figure: Gray text on light background.
High contrast (for example, dark text on light background or bright text on dark background) is required by some people with visual impairments, including many older people who lose contrast sensitivity from ageing.
Figure: Dark text on light background, and yellow text on black background.
While some people need high contrast, for others — including some people with reading disabilities such as dyslexia — bright colors (high luminance) are not readable. They need low luminance.
Figure: Brown text on dark background, and dark text on medium brown background.