Color should create a distinction between elements, with sufficient contrast.

Arizona State University

Principles and guidelines that "describe a variety of UI components and elements where color application is important."
- Consistent
- Distinct
- Intentional 

Usage in UI

Material Design Documentation

Color should be applied throughout a UI consistently and compatible with the brand.

Consistency for Color Application 

"Color should be applied purposefully as it can convey meaning in multiple ways, such as relationships between elements and degrees of hierarchy."

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