The key is establishing rules — a consistent saturation level, shared lightness values, or a defined colour system where each hue has a specific role. When colours share underlying properties even as their hues differ, the result feels intentional rather than chaotic.
Colour-coded navigation systems, category-based colour assignments, section-specific backgrounds, and data-driven colour mapping all leverage multiple colours meaningfully. The colours serve as a wayfinding system, helping users understand structure and location within the site.