Search Engine Marketing Issues: Changing URLs

I would highly recommend *not* changing your URLs at all. It is a common misconception that keywords in URLs are somehow helpful to search engine rankings, when in reality, they have very little (if any) effect on
rankings.

The reasons why people believe they help rankings are many, but generally center on a mixing up of cause and effect, as many people learning about SEO are apt to do.

For instance, when you do a keyword phrase search at Google, you will see your keywords bolded on the search engine results page, including keywords that appear in the URLs. People see this and assume that it means Google factors the bolded words into their relevancy algorithms. Yet, the software that does the bolding is just that -- software that is programmed to bold the queried words that show up in the listings. It's a huge leap to think that the bold type has anything to do with Google's actual algorithm.

Another reason why people wrongly assume that keyword phrases in URLs are a factor in getting a page to show up in the search results is because the top results do indeed often use keyworded URLs! But (and this is a big but) websites that use keyword-rich URLs are using them because someone, somewhere is attempting to optimize the pages to show up in the search results -- which means they are doing a lot more than simply putting keywords in URLs as part of their website optimization. Very rarely will you see a page show up in the search results if the only place the keyword phrase appears is the URL. Most likely the phrase is also being used in the Title tag and other visible places on the page. So again, there's a mixing up of cause and effect.

What has happened over the years is that the mixer-uppers have spread the word that keywords in URLs will help with rankings, so others believe it and make changes to their own URLs, making more and more keyword-rich URLs appear in the search engine results pages (SERPs). Which, of course, feeds the myth-monster even more!

All that said, this is somewhat of a tricky one to prove one way or another
,and it certainly doesn't hurt to use keyword-rich URLs when building a new website. It often makes it easier to remember the URL, which is why on our
new High Rankings site most of our URLs will have keywords. It's not for SEO purposes, but for usability purposes. If we didn't have to change our URLs due to switching backend platforms, we definitely wouldn't go changing to
keyword-rich file names. But since we had to change them anyhow, I figured we could use our site as a test bed to see what happens when you change URLs. (And yes, I realize we could have done some complicated things behind
the scenes to continue to keep our URLs the same as they were, but in this case, we felt changing them and redirecting was our best solution.

Especially as I can probably get a few good articles out of it later!)

I can't stress enough that you should never change URLs simply for SEO purposes. But if you do have to change them, and you do want to eke out any possible search engine benefit that you might get, then you should not use
underscores between the words, but hyphens instead. Even though Google recently announced that they were going to start reading underscores as a word separator, traditionally they haven't. They do read hyphens as a separator, however. So if Google decides to use URLs to rank pages, then you'd want to at least create them in a way they can read. You would also not want to put two words together like "twowords.html " as they don't separate words that are mashed together that way either.

Where you may benefit from a keyword-rich URL that has its words separated by a hyphen is when another site links to your page by using just the URL because it becomes somewhat of a keyword-rich anchor text link. For example,
if someone links to your page with this URL www.example.com/keyword1-keyword2 (instead of using traditional anchor text) you'd still have keyword1-keyword2 as part of the anchor text, which does tell the search engines that the page they're about to go to is at least somewhat relevant to those keyword phrases.

So in answer to the original question, instead of changing the existing URLs, make sure you've optimized the page elements that do matter --especially the Title tag, the anchor text pointing to that page, and the words on the actual page itself -- and don't worry about the URLs. Changing them can lose any "age equity" that you may have built up with your old URLs, with minimal (if any) effect on rankings.

If after all this you still feel the need to change them, be sure to put 301-redirects in place from the old URLs to the new, and use hyphens rather than underscores.

Source:http://www.isedb.com/db/articles/1759/1/Search-Engine-Marketing-Issues-Changing-URLs/Page1.html