Too me, it would be more natural to have tags with an initial upper case letter than a lower case letter, but that isn’t the case (pun intended). I hear no reason to why that is, but colleagues keep telling me to only use lower case while creating tags. I wonder if it may have to do with the fact that the tag itself is not created as a controlled vocabulary, managed by an Information Architect at all times. Instead a tag is a kind of folksonomy, driven and managed by its users from the bottom up. But I have no clue… I’m only guessing. Do you know why tags first letter is lower case?

  • 5
    Similar question on stackoverflow.com/questions/549229/…
    – Igor-G
    Commented Nov 23, 2012 at 11:58
  • One edge case to consider is all-caps initialisms, abbreviations and acronyms. For example, UK -> uk -> Uk, or OPEC -> opec -> Opec, or ETC (Exchange Traded Commodity) -> etc -> Etc. I'm not sure what the general best-practice is on acceptable tag-length, but it is something to consider. There is ample opportunity for ambiguity. In these cases both all-lowercase or first-letter-uppercase will cause trouble.
    – CJF
    Commented Nov 23, 2012 at 13:37
  • I suggest you ask this over at English.SE too. I'm sure there are some rules and guidelines for uppercase and lowercase in various situations... Bullet point lists, comma separated lists, individual buttons, search/filter specifications etc Commented Nov 23, 2012 at 15:01

3 Answers 3


Partly to do with the likely matching lower case of the word when found embedded in the relevant content.

Partly to provide a consistent nature to the tags without seeming to give any one tag preferential treatment or any sense of importance that is not due.

Partly to remove a layer of complication when creating, defining, exposing, using, sharing, translating, duplicating and implementing tags.

And importantly, partly because the tag is not a noun or a description or phrase nor any language related element - it is just a tag - a handle by which to pivot data around.

  • Good answer. Personally, I think it worth mentioning that this answer holds true for english language, but might not be entirely applicable to all languages. For example, tags that are nouns are potentially less ambiguous displayed capitalized in german language as a search for "tag wolke" shows.
    – kontur
    Commented Dec 28, 2012 at 23:21
  • I don't feel that reasons one and three here are actually that important. From a programming perspective normalizing the case of a tag for a particular implementation is trivial in almost every programming language. And in the case of full text searching the keyword will likely be stemmed to its root to search for all relevant forms of the term (e.g. tag, tags, tagging, tagged, etc). Commented Sep 3, 2014 at 16:42

Is "all lower-case" a rule?

If you google "tag cloud images", you'll find all kinds of tags.

Example from Wikipedia:
enter image description here

The advantage I see for a pure lowercase situations, is that the tags could be used in a context where lowercase makes sense.


This post is marked with tag, tagging, lowercase and question

as opposed to

This post is marked with Tag, Tagging, Lowercase and Question

  • That should easily be solved by using a ToLower function and should not be dependent on the actual tag value. Commented Nov 23, 2012 at 14:07
  • @Marjan. But what about Obama, iPhone and OpenAPI? Commented Nov 23, 2012 at 14:15
  • IMHO, tagging is like programming: Case sensitivity is a pain and should be avoided, but one should program (and tag) as if things were case sensitive... Commented Nov 23, 2012 at 14:17
  • hmm, yep, got a point there. Commented Nov 23, 2012 at 14:47
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    @TylerLangan Hehe. No problem at all :-) Some criticism from time to time is just healthy. It makes you grow... I'm glad you pointed out why, though. I haven't seen any such research, so if you have a reference/link, that would be great. Commented Nov 23, 2012 at 15:06

ba da cha Nice. Ben, this is a great point. Tags with an upper-case first letter would be more readable, according to usability research. 50 Websites Deconstructed by Jacob Nielsen talks about this.

Just because they're input in lower-case doesn't mean we can't display them with the best convention. Input!=Output. I say convert the tags to have upper-case first letters. Great idea Ben.

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