If you’re one of Google Discover’s millions of daily users, you’ve doubtless come across all manner of content without actively searching for it. A Spanish user, for instance, might see headlines promising to reveal the secret recipes of avant-garde chef Ferràn Adrià, what time 46 year-old TV presenter Pilar Rubio goes to bed, the latest unmissable deals from Lidl, or the new car that will allow them to say “adiós” to annual inspections.

We still tend to think of Google as a search engine first and foremost. The iconic search bar on a white background – Alphabet’s flagship product that underpins its substantial advertising revenue – has long been part of our vocabulary, as both a noun and a verb that has the final say in contentious debates.

But over the years, Google has established another service, one that moves beyond traditional “searching” to algorithmic “finding”. Google Discover, its content recommendation system, has a similar interface to a social media feed, though without comments, retweets or visible interactions from other users.

Unlike other Google services like Maps, Drive or Photos, Discover does not have its own app. Instead, it comes pre-installed on Android phones as an integral part of the interface, usually accessed by swiping right on the home screen.

The big question regarding this and any other recommendation system – from controversial algorithms like those on Instagram and Facebook, to Netflix, YouTube and even seemingly innocuous services like Vinted – is how it decides what content to recommend to you. What have you, as a user, done to deserve this on your phone?

When people try to explain how platforms recommend content to us, they tend to lean on algorithmic imaginaries, gossip or unfounded beliefs. Some even attempt to train or manipulate the algorithm based on these reconstructions.

However, the truth is that there is no single........

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