[karljtaylor]

Facebook and Google (and nearly every other social ads platform that evolved along the same playbook) avoid the 'personal'by aggregating users above certain thresholds. It's fairly precise, and often the only times I can spot an individual is if they're flagging something geographic or contextual (e.g., search) that is unique. (for example, I know when my parents visit my blog because I know their network hostname and location.)

when you say, begin to search for trips to disney and start looking through photos on Facebook, it isn't that an advertiser discovers you, gnode, are looking for a disney trip, it's that the platform adds you to an audience of people interested in disney and to an audience of people who are interested in travel. advertisers engage with those audiences, platforms hold the data.