Changes and revisions overview

Google Drive maintains an automatic history of modifications, which can help users track file changes and content revisions. In the revision history, users can see what edits have been made and can revert to a specific version of a file with specific edits.

These terms define changes and revisions for the Drive API:

The section of a file that has changed since its last revision, or a change to file metadata, such as file title.
User change log
A record of all changes that a user makes to every editable file such as a Google Doc, Sheet or a Slide.
Shared drive change log
A record of all changes to a shared drive, such as add or remove users to the shared drive, and all changes to files within a shared drive. A change to a file within a shared drive appears in both the user's and shared drive's change log.
Change Log entry
A record of a change to a file's content or its metadata. A change log entry indicates the user who made the change, the timestamp, and an ID. Each file in the change log can only contain one entry at a time. Each time that file changes, a new ID is created for that entry, and it replaces the previous entry. For example, if the file changes 100 times, each new entry with new ID overwrites the previous change log entry.
A version of the file that represents a change to the file contents only, not a change to its metadata such as file title. Each revision can be downloaded or published.
Blob revision
A binary file upload, such as an image, video or PDF, whose content can't be modified. If the blob revision is the only revision, it cannot be deleted. A new blob can be uploaded as a new revision, which becomes the new head revision of that file.
Revision History
A record of all revisions to a file in chronological order. A change to a Docs, Sheets or Slides file gets a new revision. Each time the content changes, Drive creates a new revision history entry for that file. However, the editors reserve the right to merge these revisions together, so the API response might not show all changes to these files.

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