I've created this question for us to document guidance around tagging. We have a lot of old tags migrated in from SharePoint Overflow 1.0 that should be sorted through, and need to set the appropriate guidance going forward. This post is intended to help us with both these things.
It's set to community wiki - adding new entries and editing existing ones is encouraged. Please remember to vote!
(This post is an adaptation of a similar one on Cooking SE so thanks to them.)
Only use version tags for questions that are truly version specific.
Do not use the 2007 or 2003 tags unless you are certain the question only applies to these specific versions.
Do not use the 2010 where the information is not specific to SharePoint 2010. The absence of a version tag should mean "current version" or "current and potentially future versions". The majority of questions that are applicable to SharePoint 2010 will likely still be relevant to the next version.
If you're not sure, just add the version information into the text of the question rather than use these tags.
Combine multiple words for a tag with a hyphen.
When entering a tag, don't use a space to separate the words in a topic. For example, use content-types rather than content types. Not doing this will result in your question being effectively untagged as it won't be found by the users that follow that topic.
Also, combine multiple words with a hyphen. Without using a separator, it makes the tag harder to read and harder for search engines to find.
Use existing tags where possible.
The system is designed to help users "follow" tags. If you create a new tag for a topic that already has one, then it serves no purpose and won't be found by these users resulting in noise.
Topics that absolutely can't be found on the system should have new tags created for them.
Choose tags with higher counts in the look-ahead prompts.
The more people following the tags you've chosen, the more likely your question is to appear highlighted or in RSS feeds.
Try to use more than one tag.
Each tag you add broadens the audience of people likely to see your question.
Avoid vaguely named tags.
The broader a tag is, the less helpful it becomes for categorising content, resulting in noise.
Part of a tag's goal is to target its audience so the people most knowledgeable in a topic can answer it.
Tag by feature, not by product.
Browsing tags by the various editions of SharePoint doesn't help when researching a topic. It's the functionality provided that's important.
If you feel it may be useful to the community to note the particular SKU you are using, please add it to the body text of your question.
For example:
sharepoint-foundation