CLS

Cumulative Layout Shift

An important user experience metric that’s part of Google’s Core Web Vitals (CWV). It measures the visual stability of a web page as it loads, focusing on unexpected layout shifts that can disrupt a user’s interaction with the page.

Here’s a breakdown of CLS and why it matters for marketers and web developers:

1. Definition: CLS quantifies how much visible content unexpectedly moves around as a page loads. This could include images, buttons, or text shifting position.
2. Measurement: CLS is scored from 0 to 1, where 0 means no shift and 1 indicates maximum shift. Google considers a score of 0.1 or less as good.
3. User experience impact: A high CLS can frustrate users, leading to accidental clicks or difficulty reading content. This can increase bounce rates and negatively affect conversions.
4. SEO implications: As part of Core Web Vitals, CLS is a ranking factor in Google’s search algorithm. Pages with better CLS scores may have a slight advantage in search rankings.
5. Common causes: Large image elements without dimensions, dynamically injected content, web fonts causing FOIT/FOUT (Flash of Invisible/Unstyled Text), and actions waiting for a network response before updating DOM.

How to Improve CLS

Google provides various tools to measure CLS, including PageSpeed Insights, Lighthouse, and the Chrome User Experience Report (CrUX). Here’s how to reduce CLS:

• Always include width and height attributes on images and video elements
• Reserve space for ad elements
• Avoid inserting new content above existing content
• Preload critical web fonts
• Minimize the use of animations

For marketers and developers, optimizing CLS is crucial for providing a smooth user experience and potentially improving search rankings. It’s part of a holistic approach to web performance that can lead to better engagement, conversions, and overall digital marketing success.

As web technologies evolve, staying informed about metrics like CLS and implementing best practices for optimization will remain essential for maintaining competitive, user-friendly websites.

• Abbreviation: CLS