user19409: What is the general procedure for deleting or merging tags that are duplicates/synonyms of other tags?
As I understand, unused tags will get deleted automatically after a period of time.
Where tags should be merged, is there a process where the less established tags get migrated over to the more established tag?

user10794: See What are tag synonyms and merged tags? How do they work?
Users with more than 1250 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.
Moderators can merge synonyms into the parent tag.

19409: <p>What is the general procedure for deleting or merging tags that are duplicates/synonyms of other tags?</p>

<p>As I understand, unused tags will get deleted automatically after a period of time.</p>

<p>Where tags should be merged, is there a process where the less established tags get migrated over to the more established tag?</p>
 10794: <p>See <a href="https://meta.stackexchange.com/questions/70710/what-are-tag-synonyms-and-merged-tags-how-do-they-work">What are tag synonyms and merged tags? How do they work?</a></p>

<p>Users with more than 1250 reputation and a total answer score of 5 or more on the tag, can <strong>suggest</strong> tag synonyms. Users with a total answer score (total upvotes minus total downvotes) of 5 or more on the tag, can <strong>vote</strong> 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.</p>

<p>Moderators can merge synonyms into the parent tag.</p>
