Google’s Hummingbird update has been described as the largest change to Google’s inner workings in years. Driven by the meteoric rise in smartphone use, Hummingbird is designed to better serve people using voice search, and to better understand complex queries.

To do this, Hummingbird shifts the search engine’s focus from keywords and search strings to meaning and context. By taking a semantic approach to searches, Google hopes to match the intent–not just the individual words–of a user’s query with useful websites.

While only Google knows exactly how Hummingbird works, there are three things every site owner and SEO should know about it.

Hummingbird is the Biggest Update to Google Search Since 2010

Since it’s launch in 1997, Google has continuously improved the algorithm it uses to determine which results to display when a user searches for particular keywords. These changes are usually minor and happen almost daily, unnoticed by users or SEOs. With Hummingbird, though, Google replaced their core algorithm entirely.

The last time Google did this was in 2010 when they launched the Caffeine update. While Caffeine was designed to provide search results faster, and to better handle the constant stream of data coming from services like Twitter and Facebook, Hummingbird is designed to change how Google’s search engine understands the web and its users’ queries.

Hummingbird Uses Entities Instead of Keywords

Instead of looking at a search query and trying to match its keywords with those it finds on websites, Hummingbird breaks down queries and website content into “entities,” the meanings of which it then matches using the same technology behind its Knowledge Graph. By matching meanings, Google can more accurately pair a user’s intent with sites likely to satisfy it.

This meaning matching allows Google to know that “closest place” and “nearest location” represent the same thing. In fact, when a user enters the query “where is the closest place to get an oil change,” Hummingbird is able to match meanings so well that Google’s search engine will now return not just a list of sites with the same words, but an answer to the user’s question.

Hummingbird Further Emphasizes a Site’s Authority

For years, Google has been giving higher rankings on its results pages to sites which it considers trusted authorities, but Hummingbird takes this to a whole new level. Because Google is essentially adjusting its vocabulary with every site it analyzes, if the search engine doesn’t trust a site, it’s unlikely to be considered at all.

In order to determine how authoritative a site is for a given topic, Hummingbird relies on a number of different criteria including the age of the site’s domain name, how much information it hosts for the topic, and how many other authoritative sites link to it. Sites which pass Google’s trust tests are not only given preferential treatment, they’re now likely to be the only sites users will see.

Here’s an article from Wired on Hummingbird.