> after searching my email accounts
here's a possibility right here - google sells a list of potential names a given user searched for, and facebook / instagram use that as a way to try to find connections
here's a possibility right here - google sells a list of potential names a given user searched for, and facebook / instagram use that as a way to try to find connections
There are lots of less well-known companies that will happily sell you lists, though, cobbled up from who knows where.
It's worse than that, they give it away. RTB (real time bidding) on advertising works by presenting the bidder with a whole pile of info on the ad slot they are bidding on.
So even if you don't bid or you lose the bid you still get all that juicy data.
https://www.iab.com/guidelines/real-time-bidding-rtb-project...
I'm finding web pages at Google showing that they run their own ad exchange, and they integrate with other people's ad exchanges.
I don't know how to find out if Google makes bids using any exchanges other their own, or whether the information from Google's bids could otherwise leak to advertisers.