Which is better for SEO an "UNDERSCORE" or "HYPHEN"?

[zartoop]

No - actually Matt knows more now than Matt did when he first posted the hyphen blog entry - I may be mistaken of course - do you have a more recent comment from him than his mid 2007 announcement?

[Windsun]

EXCEPT that recommendation is misleading and downright wrong because it's from years ago and mid 2007 (also according to cutts) google now treats underscores as word separators not joiners - therefore the complete reasoning behind the original cutts recommendation is flat out wrong. It amazes me that people can read an article and not look at the date.

If that were true, then why do I get this:

solar electric: 1,210,000 for solar electric.
solar-electric: 963,000 for solar-electric.
solar_electric: of about 895 for solar_electric.

Conclusion: Google treats underscores as a single word

[wige]

Personally, I would go with the official word on the Google web site:

Consider using punctuation in your URLs. The URL http://www.example.com/green-dress.html is much more useful to us than http://www.example.com/greendress.html. We recommend that you use hyphens (-) instead of underscores (_) in your URLs.

from URL structure - Webmasters/Site owners Help

I have seen Matt Cutts point out on several occassions that underscores have a different meaning, and that they were indexed as normal characters at one point, and even if that does change in Google, there is no guarantee that the change will carry over to other search engines.

I have seen a lot of sources conduct basic tests to try to determine which method is better (such as the test at URLs (Update)) but most of these tests are from 2007 or before. Personally, though, I tend to be conservative and if a particular method has a historical track record of being well supported, I tend to stay with it until something comes along which is demonstatable as being an improvement.

[Peter (IMC)]

Look at the urls of this forum.

[zartoop]

wige - thanks for that info - good sources (although old) and leading to a fact based answer. I am going to run some tests similar to the ones mentioned and will post the results when in. Thanks

[tushar123]

Look at the urls of this forum.

That's true Peter.

If a hyphen is placed between two words to join them, then in Google Search Results it is treated as different words,

whereas the underscore is considered as one word, and google asks you with some similar options for that result.

[Peter (IMC)]

Really it does not matter in the field of SEO, but I prefer to underscore.

Where did you get that idea from? Did you read this thread at all? It's pretty much proven that underscore is a bad idea.

But don't let that hold you back underscoring keywords in your url's..

[fazthegreat]

I used to use underscores but I read it on a few forums that hyphen is better, so now I use hyphens.

[intelinside]

Just to add a vote for Hyphens, I would also like to share an excerpt from Google webmasters Help which states that:

Consider using punctuation in your URLs. The URL http://www.example.com/green-dress.html is much more useful to us than http://www.example.com/greendress.html. We recommend that you use hyphens (-) instead of underscores (_) in your URLs.

For further reading, you can visit G webmaster help HERE

[loosapphire]

I use hyphens in my website. When I did my web construstion, I found most of people to use hyphens. I don't know the theory behind, but google tell me the truth.