It seems that search engines like to find the sames words in the page title, the URL, and the content.

In this regard wouldn't it be more efficient to separate words when building the URL out of the title, ie if the page is "computers and internet" make an URL like "computers_and_internet" rather than "computersandinternet" ?

Yours opinion  ?

I'd be interested in this also. If I could place a dash or underscore between the words that would be great. Is there a way to do this by changing the regular expression?

Better is dash, underscore is counted as whole word by search engines...

Since Morpheus research seems to have invalidated Plachow's remark, I think that the underscore _ is better than the dash -.

The dash has a meaning in itself, and is part of certain words, whereas the underscore is the natural way to replace the space ; it has no other meaning and does not exist inside words, therefore it is an ideal separator.

Beside that, it is also lighter and nicer from a typography viewpoint - it make the group of word more readable (I admit this is not the main purpose of an url though).

Conclusion, to me internet_and_computers is better than internet-and-computers

Sorry to dissapoint, but as a member of the SEO community, the underscore is NOT a valid word seperator.  Please check out this post from Matt Cutts.

http://www.mattcutts.com/blog/dashes-vs-underscores/

"So if you have a url like word1_word2, Google will only return that page if the user searches for word1_word2 (which almost never happens). If you have a url like word1-word2, that page can be returned for the searches word1, word2, and even “word1 word2″."

Scott, add the dashes bro!

This blog was written 3 years ago, and it is based on an even older experience.

I think that RubyOnRails contributes greatly to make _ the true_replacement_for_spaces (what it has always been). In many languages, the dash is part of words like in french rainbow (arc-en-ciel). Only the underscore is non-ambiguous ( or not_ambiguous) as a separator.

If you read the whole page, and not only the initial blog, you will see that this is a controversial issues. example :

http://12pointdesign.com/advice/dashes_vs_underscores.asp

Late this summer my wife (who provides primary content management support for our design and hosting business) "accidentally" used underscores for a file name on one of our sites and saw a huge and immediate increase in contextual value and search result placement for that page. Later that evening, as a test, we switched several file names for long-standing and well-placed dashed URLs to use underscores instead. We saw an immediate increase in contextual advertisements (a couple of the pages never had any contextual advertisements). In the following days, search engine placement increased and they generated more revenue than ever before. Consistently. That was when I changed my position on whether dashes or underscores are better.

I disagree.

Separators is better than _.  Checkout the official google blog:

http://googlewebmastercentral.blogspot.com/search?updated-max=2008-02-27T18%3A00%3A00-08%3A00&max-results=7

This is what matt cuts said in his august 2007 blog, much more recent than the 2005 blog that has been as base for billion discussions about underscore vs dashes (quote of the 2007 blog ):

If you read Stephan Spencer’s write-up, he says some people thought that underscores are the same as dashes to Google now, and I didn’t quite say that in the talk. I said that we had someone looking at that now. So I wouldn’t consider it a completely done deal at this point. But note that I also said if you’d already made your site with underscores, it probably wasn’t worth trying to migrate all your urls over to dashes. If you’re starting fresh, I’d still pick dashes.

Either are probably and will be equivalent in the future. Google says that they could 'probably' understand bigcat as well as big-cat or big_cat, so maybe no separator might work as well in 2 or 3 years !

That said, you must decide. Underscore is just a matter of preference, while the 100% tested and recommanded solution, past, present and future, is the dash  -

So I'm OK with Robert and many others and if I were you I would take the dash as the more universal recommandation.

Thanks to everybody who gave their opinion and links in this discussion.

Benoit

Scott, I would submit the dashes, which are currently shown to be word seperators, be the default.  Better to go with something we know is valid against something that might be valid in the future, but not now.

If Wordpress is gaining so much support from the SE's (Google, MSN and Yahoo all attended WordCamp) why not dotnetnuke.