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“Core Web vitals” … an abstract concept?
At least it felt that way when I first heard about it.

If you are looking for a quick resume. Here is mine: “Make sure specific web concepts are optimized as much as possible on a web/technical level so that the user has the best broswing experience”.

“Core Web Vitals” contributes to “user eXperience” (UX), as such it is a part as SEO factor. So this might be an extra reason to give enough attention to the “Core Web Vitals” inititiave by Google.

The 3 supporting indicators of Core Web Vitals are very cryptic.
Though very technical, the impact is always measured from the end-user point of view, so very user centric oriented.
For every webpage those 3 characteristic can be measured:

  • LCP
    Loading Contentful Paint
    Keyword: loading
    How fast will the user be able to start seeing something?
  • FID
    First Input Delay
    Keyword: interaction
    How fast will the user be able to interact with the page?Meaning click on something, scroll, …
  • CLS
    Cumulative Layout Shift
    Keyword: stability
    How stable is the web page?
    Killer are elements that start moving. Or for example an image that suddenly starts scaling down or up. Those examples are associated with a buggy user experience.

Two types of measurements

  • Raw
    Based on real-life user data.
  • Testing
    The data by doing intentional tests.
    this will be less ‘real’ as one cannot simulate the complete set of factors: network stability, Wifi, Network, CDN, used device (iPhone, Samsun, Google Pixel, … ), used OS (Android, Apple, Windows, Linux, …)

Tools that can be used

  • Chrome User Experience report
  • PageSpeed Insights
  • Web Search Console