Jakob Nielsen's 10 general principles for interaction design. They are called "heuristics" because they are broad rules of thumb and not specific usability guidelines.

Usability Heuristics
Usability Heuristics
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Usability Heuristics
grin.com
From grin.com
Usability Heuristics
Usability Heuristics
Usability Heuristics
Usability Heuristics