Privacy Herd Immunity

If this hasn’t happened to you, then you’ve probably had a friend tell you this has happened to them. They were at a party, where they talked about something random like tennis rackets, and then the next day, when they got online, they were shown ads for tennis rackets. How did that happen?

In my personal experience, a lot of people assume that since they never typed the words “tennis racket” into their phone or computer…