I had raised a tag merge request to merge pre-build-event, and pre-buildevent; and postbuild-event and post-build-event. That was about 11 months ago, and I still see these two tags even now.

How are tag merge requests handled? Is there a better way for tag merge requests other than posting on Meta?


2 Answers 2


As animuson mentioned, merges and synonyms are different.

Tag Synonyms

Take a look at the tag synonym list.

Take a tag synonym that wasn't approved by a moderator, such as:


This is a tag synonym. If you try to ask a question with the tag, you will get the following tag suggestion:

Example of a Synonym

You can still label max-width, but it recommends css and shows that the latter is a synonym of the former.

My understanding (and this could be wrong, I don't want to muddy SO with a test post), is that if you select , after posting the question that tag will automatically be changed to because that is the parent tag.

If you take a question tagged with one of the old tags, like this question tagged with (now a synonym of ) and just edit it, the will be automatically converted to .

(I just did it for this post, please see the revision history).

In the synonyms list, you will see a column called "renames", this shows the number of times that the tag has been renamed to the one it is a synonym of (it was 3 for -> , now it's 4).

There are still 96 questions with , which will stay like that until someone edits them.

Tag Merges

Take a look at the tag synonym list again.

Take a tag synonym that was approved by a moderator, such as:


You will notice that there are no longer any questions tagged anymore, as they have all been merged in to . Furthermore, if I try to ask a question with the merged I get the following tag suggestions:

Merged Sample

This time I don't even have the option to pick the tag I typed it, it just automatically brings up the default one. (This could be because there are no questions left with the old tag in the system so it doesn't pop up)


Only mods can do merges. However, not all moderator-performed synonyms are also merges (although they often are).

Also, this is all non-official, but based on my understanding of the system.

This may also be helpful: Improving Tag Synonyms


In practice, this is how tag synonyms are handled. You post a suggestion, people vote, if a mod notices and cares they make it happen, if not it doesn't happen. In theory, it goes like this:

Users with more than 2500 reputation and a total answer score of 5 or more on the tag, can suggest tag synonyms. Users with a total answer score (total upvotes minus total downvotes) of 5 or more on the tag, can vote for tag synonyms. Suggestions will be automatically approved when they reach a score of 4, and automatically deleted when they reach a score of -2.

But very few people ever check the pending synonyms to vote, even I don't normally check until a question here reminds me.

  • 2
    It should be noted that synonyms and merges are very different. A synonym only redirects a tag to another tag (and only for future uses). A merge actually retags all the questions to another tag. A synonym does not trigger a merge and a merge does not trigger a synonym (though they can both be done together). In this specific case, synonyms are not useful and should not exist.
    – animuson StaffMod
    Nov 5, 2013 at 6:19

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