What is passage indexing and what does it mean for SEO?

By Stefania Romanelli | 18 Nov 2020

In a blog post in mid-October, Google shared examples of how AI can help with search and cited passage indexing as one of them. It said: “We have recently made a breakthrough in ranking and are now able to not just index web pages, but individual passages from the pages. By better understanding the relevancy of specific passages, not just the overall page, we can find that needle-in-a-haystack information you’re looking for.”

The announcement caused some excitement and raised a lot of questions in the industry, with many people asking Google if it will now index single passages or sections of a page (it named this feature ‘passage indexing’ after all). But Google confirmed it will still be indexing full pages. The only difference is that it will consider the content and meaning of single passages versus the page as a whole when determining what’s most relevant for rankings. For this reason, you might also see the feature referred to as ‘passage ranking’ by some SEO blogs.

Specific long-tail searches often return results that don’t completely match your query, as often the perfect answer is buried deep in a page. This change caters to those queries in particular and Google estimates that “this technology will improve seven percent of search queries across all languages as we roll it out globally.”

Another point raised is how this will differ from featured snippets, where Google already shows a passage of content as a result. Google said its passage indexing systems “determine the relevance of any web document via understanding of passages. Featured snippets, on the other hand, identify the most relevant passage in a document we’ve overall determined to be relevant to the query.”

In terms of how to optimise for it, there is no quick-win answer apart from the usual “write fantastic content”. But the best way forward is to ensure you’re structuring your content clearly, with headings for different sub-topics. You should also continue doing keyword research on core and long-tail keywords in order to plan your content and match user queries, particularly for informational content.

The main implication of the change for SEO is that you can move further away from organising content on different pages, or with a certain structure, to better answer different questions. This can cause an excess of pages that are hard to maintain and difficult for users to navigate. Passage indexing means you can create content that better matches the users’ intent, in the format and length that makes most sense for them. Another implication is that the technology may also cause increases in zero-click results, with improved impressions but reduced clicks or reduced time on-site.

Passage indexing will start rolling out later this year for English language content in the US, with more languages/locations to follow.