An automatic edit summary is an edit summary that was automatically filled by the MediaWiki software. They are added during certain circumstances and when the user saves their edit without providing an edit summary. In short, the user probably did not type the edit summary.
The different automatic edit summariesEdit
|Action of the user||Auto-generated text ($1 being a variable)||Page|
|Removed all content from the page, bringing its page size to 0 bytes||←Blanked the page||MediaWiki:Autosumm-blank|
|Removed all content from the page and replaced it with other text||←Replaced content with "$1"||MediaWiki:Autosumm-replace|
|Created a new page||←Created page with "$1"||MediaWiki:Autosumm-new|
|Created a new redirect, or changed the target of an existing one||←Redirected page to $1||MediaWiki:Autoredircomment|
|Added a new category using the "Add Category" button on the bottom of articles||←Adding categories||MediaWiki:Categoryselect-edit-summary|
|Edited a gallery using the "Add an image to this gallery" button||←Editing a gallery||MediaWiki:WikiaPhotoGallery-edit-summary|
Why aren't some edit summaries listed?Edit
Some edit summaries are automatically generated like the ones above; however, they do not have a left-pointing arrow and they are not listed. These edit summaries include the "Undo" and "Rollback" functions, which automatically fill the edit summary field. "Undo" is not listed as the user has the opportunity to modify the edit summary before saving. "Rollback" is not listed as the above summaries can typically be modified or bypassed by the user, and rollback does not provide this option. Rollback also predates automatic edit summaries in the MediaWiki software and thus is ambiguous — see wikipedia:MediaWiki talk:Revertpage#AES.