The document discusses the 80/20 rule and how it can be applied to user experience (UX) design. It suggests determining the 20% of functions that are most used through analytics and prioritizing tasks and features accordingly. While the remaining 80% that is less used should not be ignored, more attention should be given to the core 20%. Examples of how companies like Fitbit and Microsoft Office have applied this principle are provided. The document also contains an exercise asking how one would design a pedometer based on the 80/20 rule.