We’ve been doing it for the last 30 years – clicking Save. Everyone is used to it – you work for a while, you press Save. You work some more, you press Save again. Things crash, you lose your work since your last Save. Or you can open the Auto-Save backup document, which is really just the computer doing a Save for you. It’s one of those things that we all take for granted, but is it time to kill “Save”? Or at least Explicit Save. By Explicit Save I mean that the user has to actually do something to say “save my work”. In an Implicit Save model, work is just remembered for you. You can find Implicit Save scattered through various operating systems. For example, System Preferences on the Mac.

Apple System Preferences use Implicit Save

Apple System Preferences use Implicit Save

When you make changes to this screen, you don’t have to click a Save button. They just happen. Implicit Save is actually pretty common on the small scale. Lots of popup windows don’t require an explicit Save step. But we don’t see it much beyond that.

I can hear you now thinking: but what if you make a mistake? In System Preferences that’s not a big deal, but what if you’re typing on your word processor and you accidentally delete whole sections of the document? Well, that’s why we have Undo, right? By now, our systems for Undo have become quite sophisticated – most applications let the user Undo – and Redo – multiple actions. (Ironically the “Undo” history for Microsoft Office products is erased when you Save.) Photoshop lets you see your Undo History and you can jump back through several levels of Undo just by clicking on an item in History list – and it will remember up to 1,000 Undo steps. That’s impressive. (Of course once you close your document, the History is lost.)

Photoshop's History

Photoshop’s History

What if we had Implicit Save and infinite Undo/Redo? What if you could open a word processing document and along with the current state of the document you had Undo all the way back to its original, blank state?

Problem: that would take up a lot of disk space, wouldn’t it?

Disk space is cheap, so I don’t think that’s an issue, except for perhaps video editing. When you’re thinking about Powerpoint slides, spreadsheets and Word processing the amount of space needed to save a complete document history is really not a big deal.

Problem: What if someone really wants to make a copy of something?

I think that’s easy enough – you keep Save As, or perhaps call it Copy. It would let you make a duplicate of a thing (and its complete History) any time you want.

Problem: Navigating through Undo History is too hard. Who wants to keep clicking Control-Z over and over again to get back to something they did last Tuesday?

Ah now that’s an interesting design problem. I love interesting design problems. Let’s dig on this a little. Photoshop has its History list (as we saw above) but it can be really hard to figure out exactly where to jump to in a long history. It’s easy to remember the commands over the last few minutes of work. But if this list were days or weeks old, how could you ever make any sense of it? Obviously merely listing the Undo history only works for recent changes, or once you’ve oriented yourself in your work.

Apple's Time Machine

Apple’s Time Machine

Apple’s Time Machine gives us a clue for another way to look at Undo. The Time Machine saves complete snapshots of documents (and Address Book entries, Photos, and more). The user can scroll over the timeline on the right and go back to a specific point in that document’s history and retrieve it. So what if you were working in your Word Processor and you had a timeline – and at any point you could “scrub” through the history of that document, go back to some earlier state and look at it – make a copy of it, copy text from it, or even revert to it.

Problem: What if you don’t want the history there?

We would have a way to erase the history – there are lots of good reasons (especially once you give a document to someone else) that you wouldn’t want to share the Undo History. Perhaps you’re sharing a document with a large audience at a conference, or a resignation letter to your boss. Plenty of good examples when you’d want to dump the Undo History.

Problem: People are used to saving

Well, yes, they are. More is the pity. Just because that’s how we’ve always done it doesn’t mean that’s always how it should be done.

Try this: work for a day and think about how it would be if all your work was being saved for you all the time. You’d never have to remember to press Save again. You’d never lose work again. You could go back to old ideas. You could open a document that you worked on last year, scrub through its history and see the whole thing being written – in essence, reproducing your own thought processes. How cool would that be?

I’m curious: I seem to remember that either the Xerox Star or the Apple Lisa that had implicit Save. Do you remember which one? Do you see other problems with Implicit Save that I haven’t mentioned? Do you think it’s time we started seeing Implicit Save and Infinite Undo in the digital things that we create? Are there applications out there that have Implicit Save & Infinite Undo – have you used them and do they work well?