When we use a color picker, we are making three choices: Hue (red, orange, yellow, green...) Saturation (from pale/pastel to bold) Brightness (from light to dark) When it comes to accessibility, it is important to remember that only brightness is visible to all users. Red text on a green background may disappear entirely for people who are color blind, have low vision, or are viewing the site in grayscale on an e-ink screen. In practice that means three things: Make sure color choices for fonts and graphic elements provide sufficient light/dark contrast against their background. Note that Princeton orange only complies at certain sizes and on certain background colors. When using colors to differentiate between elements (e.g., a link and its surrounding text), do not rely on color alone to differentiate elements the two elements -- underline the link, use a hatched pattern or segment outline in a pie chart, etc. Check your work! Use an automatic color checker like Color Contrast Analyser or WAVE. Don't do This Insufficient Color Contrast Why Is This Wrong? For people who are colorblind or are using grayscale devices (e.g., for "digital wellness" in the evening or due to migraines), red and green color hues may not be visible, so it is only the difference in brightness (the "contrast") that remains. Since these red and green colors are the same, no contrast remains without the hues. Princeton Orange (#e77500) is a fairly light color; like light gray and yellow, it does not have enough contrast on black. It is also the same brightness as the gray around it, so this link will be invisible to low vision and colorblind readers. Note that explaining the image in its alternative text only helps non-sighted users; alternative text is invisible to the users with low vision, who need the increased contrast. Here is the exact same image in black and white: Do This Sufficient Color Contrast Why is This Right? Using a secondary indicator to associate labels with chart elements means the color of the bar or segment no longer matters. In this case, the labels have been placed inside outlined segments; for line charts using different dash patterns or dot shapes could accomplish the same. Princeton orange is fine on black. And underlining the link means it can be easily detected, even if the contrast ends between the link and the text is not very strong. Here is the same chart in black and white: Testing for Accessibility Test Use automatic checkers like Color Contrast Analyser or WAVE to test your color choices. Does all small text have at least a 4.5:1 contrast ratio? Does all large text (19px bold or 24 px regular) have at least a 3:1 contrast ratio? Applicable WCAG Success Criteria Color is not the only visual means of conveying information (1.4.1) Text and images of text have a contrast ratio of 4.5:1 (with certain exceptions; 1.4.3) Visual information required to identify user interface components and states...have a contrast ratio of at least 3:1 against adjacent color(s). 1.4.11