Google is continuously looking for ways to improve collaboration. One way is by adding new activity features to make it easier to see who updated a file and how.
Google Drive
Introducing Activity dashboard in Google Docs, Sheets, and Slides! It’s a feature that lets collaborators with edit access see who has viewed the file and when they viewed it. For example, a collaborator can check if a coworker has seen a file already and alert them that it’s been updated. Or an account manager can judge the best way to follow up with a partner, depending on whether that partner has viewed the materials they previously sent.
You may have noticed a notification in Google Docs, Sheets, and Slides to explain the feature and its control options. Activity dashboard will only show viewing data for a collaborator after they see this notification. It will not display any activity from before they saw it.
All collaborators will have access to privacy settings that allow them to control whether their views show up in Activity dashboard at any time. For more information and to change settings, see the Activity dashboard Help Center.