Performance · Website glossary

Render blocking

Quick answer · What is Render blocking?

The condition in which a resource or task delays the browser from rendering content.

IN PRACTICE

Render blocking: an example

A stylesheet needed for initial presentation must be fetched before the browser can complete that rendering work.

KEEP IN MIND

Removing or delaying a resource blindly can break presentation; identify whether the initial view actually needs it.

Put the idea to work

Frequently asked questions

What is a practical example of Render blocking?

A stylesheet needed for initial presentation must be fetched before the browser can complete that rendering work.

Can I safely delay every render-blocking resource?

Removing or delaying a resource blindly can break presentation; identify whether the initial view actually needs it.

Which concepts should I read alongside Render blocking?

First Contentful Paint: FCP marks when a browser first renders qualifying content from the page.
CSS: Cascading Style Sheets define how web content is presented, including layout, typography, spacing, and visual states.