Facebook’s data scientists were aware that a small proportion of users—5 percent—were doing 85 percent of the hiding. When Facebook dug deeper, it found that a small subset of those 5 percent were hiding almost every story they saw—even ones they had liked and commented on. For these “superhiders,” it turned out, hiding a story didn’t mean they disliked it; it was simply their way of marking the post “read,” like archiving a message in Gmail.