FID measures how long it takes for your website to respond when a user first interacts with it, like clicking a link or tapping a button. This Core Web Vital tracks the delay between the first interaction and when the browser begins processing that interaction. A good FID score means your website responds within 100 milliseconds, showing search engines that your site provides a responsive user experience.
See also: Core Web Vitals, Page speed
Further reading: How to Test and Improve Website Load Time
