I wanted to post this for a while...

First off, I think that we're not tagging enough. Currently, we have an average of 2.1 tags per question. I've checked some (thematically) comparable sites, and Stack Overflow, Code Review and Programmers all have between 2.6 and 3 tags on average. Tags are a really useful concept of SE to organise the questions on the site and make it easier for people to find those they are interested in, and I think we should make use of that. I tend to do quite a lot of tag edits on new questions if I know that more applicable tags exist, but it would be nice if I could get some help with that.

In addition, while we've added a few tags for challenge types recently, it seems that some people put more effort into getting rid of tags than adding new ones. As far as I'm aware I'm one of very few people who regularly try to add new (non-challenge) tags.

At the same time, we do have a few tags that are completely useless, but still widely used. Luckily, we got rid of [algorithm] recently, but there's still stuff like , which I think is the epitome of a meta tag.

And then there's really confusing groups of tags, like , where I'm never quite sure which ones to apply to any given maths-based challenge.

So before we embark on The Great Tagging Spree, I think it would be useful if we could get a consensus on what kinds of tags we actually want. The normal definition of a meta tag ("The tag can't stand on its own") does not really apply here, since challenge tags are mandatory. Can we come up with some guidelines for how non-challenge tags should be applied and which ones we should even create or keep?

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    \$\begingroup\$ Why is [printable-ascii] a meta tag? It describes the challenge, not the post, and it's pretty clear as to when it applies. \$\endgroup\$
    – Doorknob
    Commented Mar 13, 2015 at 12:29
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    \$\begingroup\$ @Doorknob It's also completely useless. It doesn't say what the challenge is about - it describes a meta property of the challenge. Would you ever search for questions with that tag because you felt like answering a printable ASCII only challenge today? \$\endgroup\$ Commented Mar 13, 2015 at 12:31
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    \$\begingroup\$ Hmm. Actually, "would you ever feel like answering a [tag] question someday" doesn't seem like too bad of a guideline for whether a tag is useful (or more generally, "how much do questions tagged [tag] have in common?"). \$\endgroup\$
    – Doorknob
    Commented Mar 13, 2015 at 12:37
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    \$\begingroup\$ Getting rid of algorithm but not math doesn't seems quite right to me, as algorithm is just a part of math, and the later is more general. I ended up thinking time-complexity is a better tag for most good purposes of algorithm. \$\endgroup\$
    – jimmy23013
    Commented Mar 14, 2015 at 4:52
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    \$\begingroup\$ @user23013 I think we should keep math; just because it's a superset of other tags doesn't render it useless. (Consider java at Stack Overflow, which has many subtags.) \$\endgroup\$
    – Ypnypn
    Commented Mar 15, 2015 at 13:25

2 Answers 2


The question I wanted to set out to answer was — what are we doing wrong? Why do we have bad tags, and end up needing to purge them?

To answer this, I went through the top 100 tags or so and tried to categorise them:

Winning criteria

Input/output types


Language-specific tags*

Task types


*This includes questions which require answers written in the language, as well as questions using the language as a theme

(I had trouble distinguishing between the last two categories...)

That gives us an idea as to what classes of tags we might want, but doesn't directly give us a way of immediately telling if a tag is bad. But from browsing the tags above, I think the biggest problem is that there's a lot of confused tags, which aren't clear about what they're meant to cover:

So my proposal is that tags of the above classes are fine, except:

  • The tag name should be unambiguous enough so that people can get a good idea of what the tag encompasses, while preventing any possible major causes of confusion.
  • The tag wiki should clear up any possible minor confusion, and should clearly define the scope of the tag (especially for winning criteria, restrictions and task types). To be honest, I think we would benefit from more detailed tag wikis, in general.
  • The tag should ideally be broad enough to be applicable to at least a few questions, but not be too broad to the point where it's better to split it up into several smaller tags.
  • \$\begingroup\$ css is really more a "theme" than a "language-specific tag" (at least, going by the questions). \$\endgroup\$ Commented Mar 13, 2015 at 16:41
  • \$\begingroup\$ I think regular-expression and manufactoria are language-specific. And the languages-specific tags can always be used as themes. \$\endgroup\$
    – jimmy23013
    Commented Mar 14, 2015 at 3:16
  • \$\begingroup\$ @user23013 It does seem like language-specific tags fall under two types, don't they (writing in the language and using the language as a theme). Updated to reflect that. A few of the other tags also fall under more than on category, but I guess the point of this post is just to showcase what types of tags we have so far. \$\endgroup\$
    – Sp3000
    Commented Mar 14, 2015 at 3:37
  • \$\begingroup\$ Related earlier threads: meta.codegolf.stackexchange.com/questions/906/… and meta.codegolf.stackexchange.com/questions/904/…. (Also, shouldn't quine be a task type?) \$\endgroup\$ Commented Mar 23, 2015 at 1:12

This answer is to suggest a policy for what we should consider an admissible tag. It doesn't really address the question of what to do with overlapping tags, like the maths family.

As I said in the question, I don't think the guideline "can the tag stand on its own" is very useful around here on in general. I believe I've seen Grace Note or Monica Cellio post on some early beta site, that the real question should rather be whether anyone would be interested in filtering by that tag - because that's what they are for after all.

So I suggest this guideline:

Is the tag useful for filtering questions? Would anyone really want to see all challenges with that particular tag, because they're interested in the kind of challenge implied by the tag?

As an example, I personally think that this would classify as a bad tag. It describes a fairly random property of the challenge, that doesn't really tell you at all what the challenge is actually about. And I don't see anyone thinking "oh I feel like answering a printable ASCII challenge today". If they were interested in restricted source challenges, they would filter by that tag - and more importantly only 3 of the 35 challenges are even meant to be challenges. Most of the time, this is just a random feature of the challenge that isn't even intended to really affect the answers, but a mere technically (because of source layout etc.).

Please let your vote and comments indicate your opinion of the definition, not this example. Whether is ultimately a bad tag or not is a discussion for another day.

  • \$\begingroup\$ A proxy for whether people use the tag to filter questions is whether they follow it, but that data isn't available via data.stackexchange.com. I've done a bit of wget fetching and combined with post counts in this CSV file. \$\endgroup\$ Commented Mar 13, 2015 at 13:21
  • \$\begingroup\$ @PeterTaylor Thanks the data, that's quite interesting. However, we've just talked about this in chat, and I don't think this data is very reliable. I for one don't use the following feature at all on PPCG, and there are objectively useful tags that aren't followed by anyone. Furthermore, it's more an indicator of how popular a certain kind of challenge really is, rather than whether someone could be interested in filter those challenges. \$\endgroup\$ Commented Mar 13, 2015 at 13:24
  • \$\begingroup\$ xkcd would be a better tag then? \$\endgroup\$
    – jimmy23013
    Commented Mar 14, 2015 at 3:04
  • \$\begingroup\$ Should all arithmetic questions automatically math, or never math because it's redundant, or are they about different things? \$\endgroup\$
    – jimmy23013
    Commented Mar 14, 2015 at 5:03
  • \$\begingroup\$ Does filtering also include people who want to exclude all questions with that tag? \$\endgroup\$ Commented Mar 15, 2015 at 23:37

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