Who pre-sets the tags - admin or users?

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Yes, right now the tags are created as they are entered with the questions and at the moment there is no limitation to create tags.

Somebody asked for a possibility to pre-fill tags - will be done.

Also - there are management commands that rename, merge and split tags, available via the command line only at this point - they are described in the documentation.

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There is also an option to enter tags via a "category tree", which is preset by the site admins. Users still can create their own tags, but it is less likely given the choices of tags in the UI.

Thanks.

stackoverflow has good tagging system.
It even has api for tag synonyms.

http://api.stackoverflow.com/1.1/usage/methods/synonyms-for-tags

I might start implementing this for askbot.
Would anyone be kind enough to research how SO designed their DB schema? :)

We must also have an option to merge Tags - as there can be 100's of tags which are all synonyms or even Related closely. eg: #cache, #caching, #memcached, #SpeedUp etc. they all mean the same as they are all related.

I contemplated on this issue with Tagging happening in many QnA forums and here is my short proposal-

• Let Site Admins Create and set a pool of tags. But IMO, Its a good idea to Setup and finalize tags only after the site has got sufficient traction and community.

• How to handle Related and Synonyms Tags? Instead of giving admins to create options for merging; let's keep options for users TO combine and merge tags in some way, which they feel are synonyms and related tags. Let's not forget, Each user has his own version of Related or synonym.

And So this gives lots of flexibility for all users. Win-Win for all !