- A question requires at least one tag to ask.
- A new tag can only be created by users with 300+ rep
- Using a placeholder tag will get you in trouble or, in the worst case, get your question closed
- There is no entry in the FAQ about this. The validation messages don't help either.
Stack Overflow has nearly 35028 tags.
New users are supposed to find their required tag in the list.
In the worst case, say if a new user asks about HTML6 which doesn't have a tag yet, then he can tag with HTML, and:
- make it clear in the question that it's about HTML6
- ask for the HTML6 tag to be created in the comments (or even here, but that's overkill).
You should be able to find a "container" tag that is at least close to being relevant. If you can't, that's actually a huge clue that your question is off topic.
- On Stack Overflow, if your question is about the latest new version of some tool or language, and there are tags for all the old versions, there is probably a tag for the tool or language as a whole. Use that and wait for someone to create the more specific tag for you
- On the lower volume established sites, like Cooking or Science Fiction and Fantasy, don't expect to find tags for every food ingredient or every author, even though there are tags for some. Look at tags that may apply (cooking techniques like frying or braising on Cooking, tropes like magical items or alternate history on SFF) and use as many as fit your question.
- Notice there is no Recipe tag on Cooking? That's because recipe requests are off topic. Same for Health. If you're not sure whether your question is on topic or not (partly because a tag is not there) ask on the site's Meta.
The more established the site, the more likely it is that the absence of a tag is telling you something. There's no Frying tag on Stack Overflow, no Magical Items tag on Travel, no Windows-8 tag on SFF - because those questions don't belong there. But the first few Windows 8 questions on Stack Overflow were just tagged Windows. The first few C++ 0x questions were just tagged C++. And so on.
Your actions then are:
- Look for a container tag you can use
- Look for an orthogonal tag that applies
- Ask on the site's Meta what to use