It’s well established that joining a social network means trading privacy for information. Your Facebook friends, for example, get to see that picture of you looking like you might be stoned, and you get to “like” their posts celebrating the legalization of marijuana in Washington and Colorado. Or, perhaps you simply post about your 50th birthday party or celebrating Ramadan. Potential employers get to see all that stuff too, depending on your privacy settings, and there is evidence that some of them discriminate on the basis of age and against Muslims. Facebook, meanwhile, gets to target ads at you.