Start writinGoogle’s using a machine learning technology called RankBrain to help deliver its search results. Wondering how that works and fits in with Google’s overall ranking system? Here’s what we know about RankBrain.

What Is RankBrain?

RankBrain is Google’s name for a machine-learning artificial intelligence system that’s used to help process its search results, as was reported by Bloomberg and also confirmed to us by Google.

So RankBrain Is The New Way Google Ranks Search Results?

No. RankBrain is part of Google’s overall search “algorithm,” a computer program that’s used to sort through the billions of pages it knows about and find the ones deemed most relevant for particular queries.

So RankBrain Is Part Of Google’s Hummingbird Search Algorithm?

Hummingbird is the overall search algorithm, just like a car has an overall engine in it. The engine itself may be made up of various parts, such as an oil filter, a fuel pump, a radiator and so on. In the same way, Hummingbird encompasses various parts, with RankBrain being one of the newest. In particular, we know RankBrain is part of the overall Hummingbird algorithm because the Bloomberg article makes clear that RankBrain doesn’t handle all searches, as only the overall algorithm would.

What Exactly Does RankBrain Do?

From emailing with Google, RankBrain is mainly used as a way to interpret the searches that people submit to find pages that might not have the exact words that were searched for.

How’s RankBrain Helping Refine Queries?

The methods Google already uses to refine queries generally all flow back to some human being somewhere doing work, either having created stemming lists or synonym lists or making database connections between things. Sure, there’s some automation involved. But largely, it depends on human work.

Does RankBrain Really Help?

It probably is making a big impact, as Google is claiming. The company is fairly conservative with what goes into its ranking algorithm. It does small tests all the time. But it only launches big changes when it has a great degree of confidence. Integrating RankBrain, to the degree that it’s supposedly the third-most important signal, is a huge change. It’s not one that I think Google would do unless it really believed it was helping.

When Did RankBrain Start?

There was a gradual rollout of RankBrain in early 2015 and that it’s been fully live and global for a few months now.

What Queries Are Impacted?

Google told Bloomberg that a “very large fraction” of queries are being processed by RankBrain. We asked for a more specific figure but were given the same large fraction statement.

Is RankBrain Always Learning?

All learning that RankBrain does is offline, Google told us. It’s given batches of historical searches and learns to make predictions from these.

Those predictions are tested and if proven good, then the latest version of RankBrain goes live. Then the learn-offline-and-test cycle is repeated.

So when Google talks about RankBrain as the third-most important signal, does it really mean as a ranking signal? Yes. Google reconfirmed to us that there is a component where RankBrain is directly contributing somehow to whether a page ranks.

How exactly? Is there some type of “RankBrain score” that might assess quality? Perhaps, but it seems much more likely that RankBrain is somehow helping Google better classify pages based on the content they contain. RankBrain might be able to better summarize what a page is about than Google’s existing systems have done.

Or not. Google isn’t saying anything other than there’s a ranking component involved.g here...