UX ↔ How end-user experiences and feels about App

aka UX

UX Design-Focus

user-focused way of designing

References

1. usability ↔ no impact on final product & UX

2. Web Vitals ↔ metrics to QA test Web Page UX as LCP, FID & CLS vs 75th percentile page loads

3. FID ↔ First Input Delay for interactivity delay, 👍<100ms for best UX, from user action to browser response.