Which is better?
example.com/this-one OR example.com/this_one
Don’t know? I wasn’t sure either.
Let’s face it: choosing hyphens/dashes or underscores isn’t going to make or break a site’s search engine optimization (SEO) efforts. However, since all the nuances of a website’s name, title and page content play a role in on-site SEO, I thought that delving a little deeper into the great debate of hyphen vs. underscore could not only benefit me, but also my clients.
I thought that the hyphen vs. underscore issue had already been resolved once and for all. I assumed that underscores and hyphens in a Uniform Resource Identifier (URI), were all the same in the eyes of Google (and other search engines). But when I looked for confirmation on this, it was surprisingly hard to find clear evidence.
Since Google runs by far the most keyword searches, I wanted a definitive answer on which choice is best for Google search.
Doing a quick Google search on hyphens underscores seo produces a ton of articles, forum discussions and blog posts about this topic – full of opinions, facts and conjecture. I looked for the most legitimate information I could find, and since things change so quickly in web and search technology, I also looked for the most recent information I could find.
Timeline of hyphen events
In 2005, Matt Cutts (a well-known SEO guy who works for the Search Quality group at Google, specializing in search engine optimization issues) said, "For URLs in Google, I would recommend using dashes." Okay, that’s definitive, but a little out of date.
In 2007 at a WordCamp event, Matt Cutts was erroneously reported by several bloggers as saying that underscores and hyphens/dashes are the same in Google's eyes.
Cutts corrected this misinformation in his own blog post to say that Google was working on making sure that hyphens/dashes and underscores were interpreted equally, but that they were not yet the same. He followed that up with: "If you’re starting fresh, I’d still pick dashes."
The most recent Google-related information I could find was from 2009 and 2010. In 2009, Matt Cutts posted a video discussing hyphens vs. underscores, and still said hyphens/dashes are better. More recently, in June 2010, Matt Cutts and Vanessa Fox (SEO guru and creator of Webmaster Central for Google) gave an SEO review at a conference and recommended hyphens for URIs.
Searching with hyphens and underscores
It’s always good to try things out and see what really happens with search engine optimization techniques.
To see some interesting hyphens/dashes and underscores at play in Google’s search results, try varying them in searches.
Search for each of the following terms in Google.
The results are not the same. While great-example automatically searches for the version with a space, when you search for it with an underscore, you get different results.
Or for another example, type these into the Google search box:
-
allinurl:file-sharing site:mashable.com -
allinurl:file_sharing site:mashable.com -
allinurl:"file sharing" site:mashable.com
The ones with quotes or with a hyphen get the same results, such as mashable.com/tag/file-sharing/ and mashable.com/2009/02/05/box-enterprise-file-sharing/ (note the “file-sharing” bit in each URL.) The underscore version gets no results.
Certainly, a lot of subtle things are at play here. The Google search algorithm seems to be smart enough to know if you're searching for one word or two, and to help you with the results.
Sticking with the hyphen
In addition to Matt Cutts and Vanessa Fox, other industry leaders recommend using hyphens instead of underscores, including SEOmoz's Getting Started Guide, Susan Esparza managing editor for Bruce Clay and Danny Wall of SEObook fame. In the Google Webmaster docs the recommendation to use hyphens/dashes is clearly spelled out: "We recommend that you use hyphens (-) instead of underscores (_) in your URLs."
Despite promises that underscores will be given equal consideration with hyphens, the inconsistencies in the Google algorithm make the hyphen a better choice at this time. At some point the Google algorithm may treat this-one and this_one in URIs the same, but in the meantime, they’re simply not.
Even if hyphens and underscores are eventually considered the same, I'm still sticking with hyphens. Better track record, better usability, and frankly they just look better.
How about no separator?
example.com/thisone is not as good of a choice as either the hyphen or underscore version because there is no word separation at all. Google Search is smart and can often figure out which words are intended to be separated, but it’s best to give as much help as you can. For other reasons to use a word separator, see the usability section below.
Want a little background?
Google initially treated hyphens as word separators, and underscores as part of the same word. So in http://example.com/key-word was equivalent to “key word”, but “key_word” was not equivalent to “key word”.
URI? Don’t you mean URL?
Though a little less familiar, URI is the correct term here, not URL. (URL is the main domain part of an address, e.g. themetaq.com. URI is the directory or page name part of the address, e.g. themetaq.com/about)
Google? What about other search engines?
In late 2007, Barry Schwartz wrote an article confirming that Yahoo, Microsoft, and Ask treat underscores and dashes the same.
Still not sure about hyphens or underscores?
- Underscores are hard to communicate. Try saying each of these aloud: acustomurl.com/folder_name/ or acustomurl.com/folder-name/
- Many technical words use underscores as part of their name
- Underscores disappear in underlined links which can lead to miscommunication of saying, repeating or typing URLs. example.com/hidden_underscore
What about hyphens in domain names?
The hyphen preference does not apply to root domain names, where separating words with hyphens is not recommended at all. (e.g. themetaq.com is a far better choice than the-meta-q.com).
What if a site already uses underscores?
Don't change the URL structure if it already has underscores. Underscores work just fine. It’s OK for now, just be consistent. Consider building new sites with hyphens.
References:
Matt Cutts: Dashes vs. underscores
Matt Cutts: Whitehat SEO tips for bloggers
URL Structure from Google's Webmaster Central
It’s Not Just Google That Treats Underscores Like Dashes
Discussion from Webmaster World Forum
SEOmoz: Hyphen vs. underscore
Matt Cutts still says use dashes
Hyphens vs. Underscores – Who Wins “Best Keyword Separator?”
SEOmoz's The Basics of Search Engine Friendly Design & Development
Google Site Reviews with Matt Cutts and Vanessa Fox
Alternative Discovery & SEO: Feeds, PDFs & Blog SEO
Do You Need To Use URL Rewriting?
What others are saying
Jenn Lukas
Hyphens all the way!
http://thenerdary.net/articles/entry/hyphestaria
Being clearly distinguished visually is probably the biggest one for me. But also the overflow problem: http://hyphens-separate-words.tumblr.com/ is enough for me to always use hyphens.
Susan Snipes
@Jenn Yeay, I’m glad to hear even more excellent reasons to use hyphens. Hyphens are the clear winner!
Simon Cox
After all these years arguing this one I still believe Google have this one grammatically wrong but I have switched over to using hyphens due to the commercial implications. It is a compromise based not on language or usability but an arbitrary set of technically related decisions.
Jenn, being clearly distinguishable is easier with the underscore not the hyphen and you get the correct meaning of hyphenated words as they stand out. The non wrapping issue is a poor excuse as you don’t need to write all that out on a page - just give a link - no one is going to read or remember a link that long in the example you gave.
However. Google still does not treat hyphens and underscores equally and that’s the killer in this debate - a commercial reason and nothing else matters.
Yes hyphens are a clear winner, aren’t they.
Canto Voz Viva
Thanks for the very solid post, with strong sources. So many write just what they think without knowing more in real. I´ll gladly look through oter articles of yours if you are that serious all the time.
I´ll keep investigating for that same question on URI (with our without dashes), but your answer on URLs is already helping a great deal.
With regards,
Olivier.
Ed Gonzalez
I think either one can be used and get the same result. Search engines don’t discriminate between hyphens or underscores.
Visit-or
I’ve always used hyphens based on some article I read years ago. It said to use hyphens because Google deemed them more user friendly in reference to screen readers for blind visitors.
This could very well be misinformation… Did you come across anything on this angle for separators?