This is the new world that Apple is creating. Where your data resides, the device you use to access it, how it is saved, where it is saved, how to manipulate it, how to back it up, how to recover if you make changes to it that you did not intend, all will be things you don’t have to think about.
Your data will be available to you on any device you own. It will be left exactly as you last left it. You can open it in any application that it is able to open it. Should your computer crash, do not fear, your data is safe. And when you get a new machine, simply log into it and all of your data will be there in short order. Buy a new Mac, a new iPhone, and new iPad, simply log in and the data will be there too.
This is indeed a radical shift. One so big I don’t think any of us really understand it at this point. In some ways, Apple’s using iCloud to make thin clients. But thin clients with excellent, rich native applications.