Way cool. That is about it. It works and is way cool. The trick, you must have a second large HD to back up to. I won’t try and summarize what Apple has already posted here but it certainly does work as advertised. Select a folder, click the way back machine (Time Machine icon) and a whole series of those windows, receding into the distance of a starry field, will appear. Select on the file you want to retrieve and click on “Restore” and everything zooms back into the present, with the retrieved file. Very nice indeed for those times when we want to recover that phrase or paragraph we wrote last night and in a fit of pique deleted. (My guess is that you would need to save your current version with a new name so that the recovered file doesn’t overwrite the current one. More play is needed to suss this out.)