The Cambridge Analytica/Facebook scandal that has captured the media spotlight in recent weeks is a reminder that online security threats are amplified by the ever-expanding reach and power of the digital world. They may seem abstract and less urgent than dangers in the physical world, but their consequences are no less alarming. While I and many others have been talking about how to address them for a long time, I want to take this opportunity to underline the two main pillars of defense we can put up to protect ourselves, collectively and individually.