TL;DR
Render-blocking resources are external CSS and synchronous JavaScript files in the document head that the browser must download, parse, and execute before it can render any pixels of the page.
What is Render-Blocking Resources?
Render-blocking resources are external CSS and synchronous JavaScript files in the document head that the browser must download, parse, and execute before it can render any pixels of the page.
Fixing this in WordPress? See our step-by-step guide to eliminating render-blocking resources in WordPress, or work with us through our done-for-you speed optimization service.
How Render-Blocking Resources is Measured
Lighthouse and PageSpeed Insights identify render-blocking resources with the 'Eliminate render-blocking resources' audit.