Think of iCloud Drive as a central hub, a place for all the iCloud documents you have. It’s a cloud storage at its core, similar to Dropbox, and you can view and automatically sync docs.
"We all know that docs in the cloud provides a convenient way for working on something across platforms," Apple’s senior VP of sofware engineering Craig Federighi said on stage.
If you are wondering how will this work on the mobile side of things, on iOS, there will be a document picker that will allow you to tap into the iCloud Drive storage. We’ll be looking for more details to surface soon, as we expect Apple to release them right after the ongoing event ends.