Users won’t read web content unless the text is clear, the words and sentences are simple, and the information is easy to understand. You can test all of this.| Nielsen Norman Group
The interaction cost is the sum of efforts — mental and physical — that users must deploy in interacting with a site in order to reach their goals.| Nielsen Norman Group
Search engine users click the results listings' top entry much more often than can be explained by relevancy ratings. Once again, people tend to stick to the defaults.| Nielsen Norman Group
Interactive elements must be at least 1cm × 1cm (0.4in × 0.4in) to support adequate selection time and prevent fat-finger errors.| Nielsen Norman Group