Should tags use comma or space

Question

What is your opinion on whether a tagging user interface widget should require commas or spaces as the delimiter? For example, this site uses spaces, requiring multi-word tags to use a hyphen. I assumed this was some design suggestion from Joel; but then I realized that Facebook and Wordpress use commas.

So what should it be? Or does it not matter much? Let's suppose the users of this widget are generally computer literate but not terribly so.

Answer 1

I would try to think about the domain of the tags and figure out what is the likelihood that potential tags would contain spaces.

For example, most things on this site are single word or acronyms, so it's not difficult to use spaces.

On the other hand, when tagging facebook photos, for example, an average tag is something like "spring break", "frat party", "random hookup", "secretary of state", etc. So dealing with space interpretation or with quotes is more difficult, hence commas make more sense.

I'm not familiar with a specific rule.

If you're thinking of tag clouds though, spaces make less sense.