A few years ago Facebook had less stringent limitations on its ad targeting, and I believe Chris Soghoian was able to target ads to individual people (from the

A few years ago Facebook had less stringent limitations on its ad targeting, and I believe Chris Soghoian was able to target ads to individual people (from the Google public policy team, if I remember correctly) by specifying enough intersecting demographic criteria related to each individual target. This probably doesn't work anymore because big tech companies have gotten stricter about how small the pool of targets for a demographically-targeted ad campaign can be. At one point, you might have been able to create a non-retargeting-based ad campaign that would only have targeted your friend! Edit: another amazing example using a different method is discussed elsewhere in this thread at https://news.ycombinator.com/item?id=21094682 https://news.ycombinator.com/item?id=21094682.