So you may adamantly claim Facebook must have listened in on your private conversation yesterday about a friend’s wedding and then served you an ad for tailored wedding suits because you have not googled anything wedding-related in years. But there are scores of other data points the system has on you to determine what you should see at any given point. Not only does the system know exactly where you are at every moment, it knows who your friends are, what they are interested in, and who you are spending time with. It can track you across all your devices, log call and text metadata on Android phones, and even watch you write something that you end up deleting and never actually send.