The tighter the mapping between icons and the thing they represent, the easier they are to understand, but standardization can also make an icon easy.| Nielsen Norman Group
People rely on menus to find content and use features. Use this checklist to make sure your menus do their job.| Nielsen Norman Group
Whether you adopt a flat-design style or not, interactive components must retain sufficient cues to suggest clickability.| Nielsen Norman Group
NPS is a loyalty metric that correlates well with perception of usability, is easy to understand and administer, but has limitations for understanding and evaluating UX when used in isolation.| Nielsen Norman Group