The smartphone has been the undisputed home of social media for nearly two decades, but a quieter shift is happening a little further down the arm. Smartwatches, fitness bands, and now smart glasses are steadily absorbing more of the social experience, turning a glance at your wrist or a tap on the temple of your …...

For two decades, the deal at the heart of social media was simple and unspoken. You got the service for free, and in exchange you became the product, your attention packaged and sold to advertisers. That bargain built some of the largest companies in history. But it is now visibly cracking, and the platforms are …...