Facebook’s apology-and-explanation machine grinds on, with The Social Network™ posting detail on one of its most controversial activities – how it tracks people who don’t use Facebook.

The company explained that the post is a partial response to questions CEO Mark Zuckerberg was unable to answer during his senate and Congressional hearings.

It’s no real surprise that someone using their Facebook Login to sign in to other sites is tracked, but the post by product management director David Baser goes into (a little) detail on other tracking activities – some of which have been known to the outside world for some time, occasionally denied by Facebook, and apparently mysteries only to Zuck.

When non-Facebook sites add a “Like” button (a social plugin, in Baser’s terminology), visitors to those sites are tracked: Facebook gets their IP address, browser and OS fingerprint, and visited site.

If that sounds a bit like the datr cookie dating from 2011, you wouldn’t be far wrong.

Facebook denied non-user tracking until 2015, at which time it emphasised that it was only gathering non-users’ interactions with Facebook users. That explanation didn’t satisfy everyone, which was why The Social Network™ was told to quit tracking Belgians who haven’t signed on earlier this year.

Source: Facebook admits it does track non-users, for their own good • The Register