Documents in the Cloud iOS apps have never had Save commands; the design of iOS is such that documents are always saved continuously, in the background, without your having to do anything manually. Documents in the Cloud takes that concept a step further: your documents are not only saved locally, on the iOS device itself, but also uploaded to Apple's servers--automatically and invisibly--while you work. And, in Mountain Lion, Documents in the Cloud is extended to many Mac apps too. Apart from giving you a backup copy of your document that you could use if your iOS device or Mac were ever lost or damaged, Documents in the Cloud lets all your devices share documents with each other seamlessly. For example, you can create a document on your Mac and then continue working on it later on your iPad, without ever having to explicitly save or sync. (To a certain extent, you can also share documents with your pre-Mountain Lion Mac or your PC, too--although, as we'll see, that process isn't as smooth.)