Cumulative Layout Shift or CLS is the measurement of all layout shifts that take place as a webpage loads.

A layout shift occurs when a webpage moves the rendered resources within the browser as more resources are loaded. 

Why Does Cumulative Layout Shift Matter?

Cumulative Layout Shifts impact your overall page load experience, as the more layout shifts that take place, the longer a page will take to render.

As layout shifts occur, buttons that appear on a page as well as other content move from one place to another.

This provides poor user experience, as the content a user was reading moves, or a button that they were about to click moves, making it difficult to complete their desired action.

Too many shifts in layout also give off a shady appearance to end users, which will diminish their trust & make them less likely to complete your site’s conversions.

Webpages should always be published to load with as little movement in large layout shifts as possible, to inspire user trust & provide them with the most seamless experience possible.