This tip is excerpted from Google Drive & Docs In 30 Minutes by Ian Lamont, part of the In 30 Minutes™ family of technology guides.
If you are the owner or editor of a shared document, you can revert to earlier versions of a document, even if other collaborators have made changes.
It gets better: If you decide that you don't want to stick with the earlier version (or your collaborator demands that his version is brought back to life!) you can restore it.
There are some limitations to working with revisions, particularly for non-Google formats. Here's what Google's help pages have to say:
"Google Drive on the web keeps the latest and previous versions of a file, automatically deleting previous versions only when they're older than 30 days or there are more than 100 previous versions of the same file. While you can reverse this setting so that some of your versions are never deleted, keep in mind that you may need to purchase additional storage since these versions take up storage space in Google Drive on the web."
However, for Drive files created with Google Docs, Sheets, or Slides, you can revert to the earliest version of a document, spreadsheet or presentation, without any penalty or risk of deletion.
How To Revert To An Old Version Of A Google Drive File
1. Open the document, spreadsheet or presentation.
2. Go to File>See Revision History.
3. The Revision History will appear on the right side of the browser screen, with a list of all of the saved revisions and the people who made them.
4. Select an earlier version to view it onscreen.
5. Click the Restore This Revision link to revert to that version.
6. To go back to the most recent version, bring up the Revision History and find the version that you want to use (it should be near the top of the list).
Ian Lamont is the author of Google Drive & Docs In 30 Minutes. For additional tips and videos on how to get the most out of Google Drive, visit the official book website for the Google Drive guide.