What are core web vitals? Do they affect SEO?

Every year is turbulent when it comes to SEO, but this one may have been more so. We have seen several core updates like the one in May. Or the most recent one -in this very month of December...-, Google Lens threatening to transform SEO for images, new deadlines for Mobile First Index...

With the usual noise, together with everything that coronavirus has generated in eCommerce and society itself, it is possible that something called core web vitals has gone unnoticed by many. Do not overlook it because it will have some weight in SEO strategy for 2021.

As you may know, Google prioritizes user experience in many ways.  This, which is nothing new, was reflected in the relevance of the loading speed -to the point of being considered a ranking factor- or the reports and notifications about usability that it shows us in Google Search Console.

Core web vitals are along these lines. In fact, it is not a tool like Google PageSpeed or Lighthouse: it is a series of metrics that the search engine considers basic for the user's optimal browsing experience.

All these core web vitals are framed within the usability or, even more evidently, the performance of the page. These are guidelines that we must follow and have controlled.

Let's see what they are.

To sum it up in some way, we talk about the time that passes between the user clicking on the link and finishing loading the largest block of content below the scroll line (no matter the type of element, it can be from text to an image or a video).

The key to this metric is that it always focuses on the user, not so much on any other technical aspect. What it really measures is how long it takes for the page to become interactive and operational for the visitor.

This analysis can be extracted with the aforementioned Google PageSpeed. It has the advantage of being really visual and can give you concrete clues on how to solve it (although if you do not have a very technical profile you may need help with this).

The disadvantage is that this calculation is done exclusively from Chrome browser. The most reliable thing is that you look directly at the Google Search Console reports (key metrics).

In which parameters should the LCP be moved? Well, as reference:

It may seem similar to the PCL but there is an important nuance. While the first metric refers to the time the page needs to be ready for use, FID measures real interactivity.

In other words, we use this core vital web to measure the click response speed of the person browsing our site. This includes clicking on a link, choosing an option from a menu, entering text into a form, which takes time to respond to a drop-down menu...

For Google the priority is always the experience without friction, as smooth as possible for the user to feel satisfied. In certain URLs of our eCommerce, the FID can even represent a difference between a decent and a very poor conversion (checkout, registration...).

You can also quickly check the FID of your page by the same means: Pagespeed and Google Search Console.

In which parameters should the FID be moved? For reference, this would be the scale:

This is a simple concept to understand but not so simple to explain. It refers to the visual stability of a page.

What is that? I will give you a simple example. Imagine that you enter a website where, even though it has not finished loading, you can already start browsing. When you are going to click on a button... a photo is loaded and you "lose that click".

I am sure it has happened to you a thousand times and is as uncomfortable for you as it is for any of us. Well, this is exactly what Google measures with the CLS.

What parameters should the CLS move in? In this case it does not measure in time but uses its own scale that you can check here if you are interested in knowing how it is calculated. Within that scale:

As of today, it is not... I insist: today. The forecast is that by May 2021 they will go from being a recommendation based on good practices to a factor that influences the SEO ranking of any page.

How important? That is difficult to know right now (I doubt it is a determining factor), but everything it adds up to is interesting. And, in this case, it improves the way we interact with our store and that optimizes eCommerce at all levels and, particularly, for the user.