📘 Classic Insight: Blue is the Gold Standard
Blue underlined links are the most universally recognized and trusted.
This convention comes from early web design (e.g., Mosaic, early HTML), and users still associate blue with interactivity.
👉 Jakob Nielsen, a leading usability expert, famously emphasized that violating blue-underlined conventions can reduce usability, because users may not recognize other styles as links.
📊 A/B Testing in Practice
Google tested 41 shades of blue for links in Gmail/Ads and found that even slight color differences impacted click-through rates (CTR) significantly — reportedly earning $200M+ in extra revenue by choosing the optimal blue.
🟦 The shade chosen was a pure medium blue (#2200CC).
🟪 Slightly purpler blues underperformed by comparison.
🎨 Other Color Observations
Contrast matters more than color: high contrast between link color and background = more visibility = more clicks.
Red links can draw attention but are often associated with warnings or errors — can backfire.
Green and orange links sometimes perform well if the rest of the UI uses muted colors — they stand out more.
Underlining remains a key signal. A non-underlined colored link is often overlooked.
✅ Best Practices (Based on Studies and UX Research)
Use blue (e.g., #1a0dab, #0000EE) for primary links unless strong branding requires otherwise.
Ensure high contrast with background and surrounding text.
Maintain visual consistency — links should look clickable.
Use hover states (e.g., underline or color shift) for affordance.
Avoid using link colors for non-clickable elements.