Google is introducing major changes to the Core Web Vitals, which are essential metrics for providing great website user experiences. The focus is now on responsiveness, i.e. how quickly a page reacts to user interactions.

The current main metric, called First Input Delay (FID), has some known limitations. So Google developed a new experimental metric called Interaction to Next Paint (INP). After a year of testing and community feedback, INP has proven effective and will no longer be experimental. From March 2024, INP will replace FID as Core Web Vitals' primary metric for measuring responsiveness.

Na Google team blog post, the reasons behind this change, what is changing, and how developers can prepare are covered. It's also recommended to check the Google blog for more information on how this change affects Google Search.

INP is a more comprehensive metric than FID as it considers all interactions during the lifetime of a page, measuring the time from the start of the interaction until the browser is able to paint the next frame. This makes the INP a more accurate measure of users' perceived responsiveness.

If you want to improve your site's INP, Google provides a guide to INP optimization with detailed guidelines. It is important to highlight that many sites have a good FID performance, but an INP that needs to be improved. Therefore, it is critical to focus on optimizing the INP to deliver a better user experience.

It is important to understand the difference between the INP and the FID. While the FID only measures the first interaction and the delay of that interaction, the INP considers all interactions and measures the overall responsiveness of the page.

Google provides a variety of resources and guides to help developers improve INP, from identifying slow interactions to optimizing using lab data.

These changes to Core Web Vitals can impact your site's ranking in organic searches, so be aware.