Which is better - underscore (_) or hyphen (-)

I just wondered which one is better for the URL structure and SEO friendliness of my new directory - underscore or hyphen?

Which URL will be more SEO friendly:

www.mysite.com/directory/art_history/
or
www.mysite.com/directory/art-history/

Currently it is set to underscore but i think that the hyphen will be better... so i am thinking of changing it.

What do you think?

 

Hyphen is better.

 

Ive always used hypens and think they are actually better for SEO , but havent seen any conclusive evidence !

Best of Luck!

 

i-like-this.html because it can be typed with a regular key, instead of holding down the shift key.

Also it's more aparent that's it's seperated with a - but the _ in certain situations looke like there is no underscore and is just seperated by a space.

For example www.domain.com/under_score.html looks like a space in the URL when it isn't.

 

hyphen! easy to type http://classic-tv-shows-on-dvd.blogspot.com

 

Hypen is better in my view.

 

Hypen is better than underscore

 

hyphens are treated like spaces by Google - Underscores aren't - do a bit of research with searches and you'll see.

 

Only Hypen!
Hypen is better in my view.

 

Thanks to all!

Now i am going to remove these undersores

 

it all matters if how people find it to type ....i mean which is easier will help

 

Hyphen is better in my opinion. jimbob pointed out a big reason why to use hyphens

 

This should help to clarify the issue:
http://www.mattcutts.com/blog/dashes-vs-underscores/

Quoting Vanessa Fox posting in Cutts' blog:

http://www.mattcutts.com/blog/guest-post-vanessa-fox-on-organic-site-review-session/

 

Hypens look better, both for the reader and Google - if you ask me.

 

You all are right. I replaced the underscores with hyphens and now everythibg looks better - for me, for SEs and for my visitors too

10x again.

 

BINGO! We have a winner!

 

I never even considered the 'ease' benefit in typing the urls. Glad I caught this thread, I've got a lot of changes to make.

 

read http://www.mattcutts.com/blog/dashes-vs-underscores/ and this has been discussed before . if you search , you can find the related thread easyly

 

I guess many of us know dashes are treated better than underscores as jimbob said.

Although I never have looked at the practical side and usability of dashes versus underscores. And I like what sweetfunny has mentioned.

Something so basic but I never paid much attention to it.

 

always hyphen!