In Lion when you try to save a document you no longer have the option to “Save” or “Save As” that was available in Snow Leopard and previous operating systems. The first time you save a document you will be allowed to name and save it. After that, your only option will be to “Save A Version”.
This feature works independently and you do not have to have Time Machine set up for Versions to work.
Successive versions of any document are automatically saved periodically. Depending on your job or lifestyle you can probably imagine times when you make changes only to discover you need to revert back to an earlier version because…… well, fill in the blanks.
All you have to do is select “Revert to Saved” from the File Menu,
and much like Time Machine, you will be given a menu of all the saved versions of your document.
The page on the left is the current version. The ones on the right are the various saved versions. I can click on any of the earlier versions and get the time it was saved and then choose it by clicking the restore button or I can click on a different earlier version and keep checking until I find the one I need – at which point I click the restore button.
Note: You can always save as you go if that is your habit. Simply click the “Save A Version” button at any time.