Official Google Webmaster Central Blog: Updating our technical Webmaster Guidelines

Webmaster level: All

We recently announced that our indexing system has been rendering web pages more like a typical modern browser, with CSS and JavaScript turned on. Today, we’re updating one of our technical Webmaster Guidelines in light of this announcement.

For optimal rendering and indexing, our new guideline specifies that you should allow Googlebot access to the JavaScript, CSS, and image files that your pages use. This provides you optimal rendering and indexing for your site. Disallowing crawling of Javascript or CSS files in your site’s robots.txt directly harms how well our algorithms render and index your content and can result in suboptimal rankings.

Updated advice for optimal indexing

Historically, Google indexing systems resembled old text-only browsers, such as Lynx, and that’s what our Webmaster Guidelines said. Now, with indexing based on page rendering, it’s no longer accurate to see our indexing systems as a text-only browser. Instead, a more accurate approximation is a modern web browser. With that new perspective, keep the following in mind:

Source: Official Google Webmaster Central Blog: Updating our technical Webmaster Guidelines