Sandboxing. All third party apps in the Mac app store, and many system apps. Safari, Mail, Messages, FaceTime, Calendar, Contacts, Photos, Notes, and Reminders

Sandboxing. All third party apps in the Mac app store, and many system apps. Safari, Mail, Messages, FaceTime, Calendar, Contacts, Photos, Notes, and Reminders are all sandboxed. I also really like how Gatekeeper ( https://en.wikipedia.org/wiki/Gatekeeper_(macOS) https://en.wikipedia.org/wiki/Gatekeeper_(macOS) ) works – it quarantines documents such as word files, so that on first open you get a dialog pointing out that it's been downloaded. This is great, because you see the dialog very infrequently. I actually pay attention to it when it comes up.