Can anyone tell me if hyphens help or hurt a URL?

I would say too many can hurt. A good general rule of thumb is to ask yourself: “Does this help the user?”

If yes, do it. If not, don’t.

Hmmm. For example, if the URL has three words in it, you’d need two hyphens. That would make things clearer than a URL with three words and no hyphen, right?

I’m not sure there’s any “right” or “wrong” answer to this. Our domain, for example, is three words. But there are no hyphens.

I think part of it is personal preference, too. Some URLs just look/feel better hyphenated and some don’t.

Look at the difference:

internet-marketing-monitor.com
internetmarketingmonitor.com

The second one just “feels” better.

I’ve heard that if you hyphenate, the search engines will stop at the first hyphen and not index the other keywords. But I’ve only heard that once and it was quite a while ago.

As a result I’ve always left out the hyphens. But lately I’ve launched a subdomain and the individual file names have 4-5 words in them. That’s an awful lot of words without breaking them apart with hyphens, but I want to be careful about it. I guess I should just test it.

P.S. Is the proper form of the word “unhyphenated” or is it “un-hyphenated?”

We use hyphens in our individual file names and have had no problems getting them indexed.

Matt Cutts from Google says that hyphens are not penalized in Google.

Oh… and I believe it’s un-hyphenated ;)