Spying is accomplished mostly through connected personal devices—especially, for now, smartphones—that people keep practically glued to their bodies. Data are gathered about each person’s communications, interests, movements, contact with others, emotional reactions to circumstances, facial expressions, purchases, vital signs: an ever growing, boundless variety of data. If you’re reading this on an electronic device, for instance, there’s a good chance an algorithm is keeping a record of data such as how fast you read or when you take a break to check something else.
