Chatting with webmasters often reveals widespread beliefs that might have been accurate in the past, but are not necessarily up-to-date any more. This was the case when we recently talked to a couple of friends about the structure of a URL. One friend was concerned about using dynamic URLs, since (as she told us) "search engines can't cope with these." Another friend thought that dynamic URLs weren't a problem at all for search engines and that these issues were a thing of the past. One even admitted that he never understood the fuss about dynamic URLs in comparison to static URLs. For us, that was the moment we decided to read up on the topic of dynamic and static URLs. First, let's clarify what we're talking about:

http://googlewebmastercentral.blogspot.com/2008/09/dynamic-urls-vs-static-urls.html

You can't blame webmasters, when Google has said various different things over the years. For example, the current webmaster guidelines say this:

   "Google indexes ... pages with question marks in their URLs.
   However, these pages can cause problems for our crawler
   and may be ignored."
   http://www.google.com/support/webmasters/bin/answer.py?answer=34431&ctx=sibling

My own experience with various websites is that my pages have been indexed just as well whether they expose the dynamic parameters, or whether they rewrite them.

Google has some specific hints and tips here:

"Creating a Google-friendly URL structure"
http://www.google.com/support/webmasters/bin/answer.py?answer=76329&ctx=sibling

Incidentally, both of Google's pages linked above are using dynamic URLs, and are indexed just fine by Google and by Yahoo.

(PS: when checking Yahoo I see that the Yahoo logo is an animated Flash widget which after a while overlays the slogan "start wearing purple". Please Google never do this.)

Approaching this from a different perspective, parametrized URLs may hurt your Google rankings for a different reason: some people may be less likely to understand they're permanent & linkable and so on. Compare the two following:

example.com/product/382392/
vs
example.com/product.cgi?id=382392&mode=shop&template=pretty.xml&etc

... all other things being equal, which looks more linkable? (And the more backlinks, the higher the search ranking for a page, very roughly speaking.) It's not just that the latter URL style looks less "permanent", sometimes these kind of URLs indeed are less permanent, and sometimes you also don't quite know which parameters may reveal personal information, which may make you more reluctant to say, paste them in a forum...

More realistic would be:

example.com/product/382392/
vs
example.com/?product=382392

Sometimes there's a bit of an above average overlap between parametrized URLs and ugly URLs, perhaps because people caring about pretty URLs would use htaccess rewrites in the first place? Or differently put, I didn't come across as many "ugly" rewritten URLs as parameterized URLs in the past. I guess something makes people use more parameters when they don't use prettified URLs. Take the following URL for instance:

www.youtube.com/watch?v=nNOohFst9Lc&eurl=
http ://www.techcrunch.com/2008/09/12/bill-gatesjerry-
seinfeld-commercial-2-i-remain-confused/

Here, the full referrer URLs is added to the URL, perhaps even causing some minor PageRank splicing, not to mention that the URL becomes ugly and thus perhaps slightly less linkable (not that YouTube has any problems with rankings, but it also seems they're not heavily optimized – didn't they at one time have lots of titles with the exact same content, too?). Somewhat more rarely would you see the same URL as above, including the referrer, as a rewritten one without GET parameters. E.g. I guess like this

www.youtube.com/watch/ref/www.techcrunch.com/2008/09/12/bill-gatesjerry-
seinfeld-commercial-2-i-remain-confused/

Maybe the real issue here is that Google has seen a lot of URL rewriting where the session IDs and other session-sensitive data have not been removed.

I certainly find a lot of such URLs in Google's search results, in both formats.

Google tends to forget there are still other search engines... and they don't handle dynamic URLs as good as Google!

After spending the last few weeks in a 0 page rank world at google, im pretty sure that i would not have decided to rewrite my dynamic content. However google telling us that googlebot is smart enough to know that my parameter cat=1 is the same as /Lawn-Fertilization-Weed-Control/ is ridiculous.

Like I said I have been in the “sandbox” that doesn’t really exist for three weeks now except for a three day stretch where my site escaped. That was pretty cool. I still have over 90,000 links in the index and google recently gave me the option to increase the speed of goolgebot (not sure why).

Anyway here is an example
http:// myservicelocator.com/searchresultstest.asp?zip=48371&topcat=1&subcat=1&rad=5

Compared to this
http:// myservicelocator.com/Lawn-Fertilization-Weed-Control/48359/

You tell me what I should be doing.

Jason

[Unlinked the urls for Jason – Colin]

myservicelocator.com/searchresultstest.asp?zip=48371&topcat=1&subcat=1&rad=5&Company=Advance%20Pest%20and%20Mole%20Solutions

Compared to this

myservicelocator.com/Lawn-Fertilization-Weed-Control/48359/

You tell me what I should be doing.
Jason

Of course the other consideration is /rates/ca_rates is much better for SEO than /rates?st=ca.

Maybe Google is trying to crack down on some of that. WordPress and other blogging platforms make having optimized URLs for Dynamic content very easy.

I would continue with the rewritten URLs.

From my understand on this. Google is simply saying, that you should use static URLs only where your users benefit. For example, example.com/blog instead of example.com/index.php?page=blog

However, they are saying that in other cases, eg. search, you should use dynamic URLs so that Googlebot can attempt to work out what is and isn't a search result (eg. example.com/search.php?q=keyword is far more distinguishable then example.com/search/keywork).

I believe they're referring to something like:

example.com/search.php?q=keyword

transformed into:

example.com/search/keyword.html

or

example.com/blog.html

example.com/blog/tag/google.html

'blog' : file or dir?

I guess a RESTful approach would say use rewriting to create meaningful URLs.

In the case of search, the input parameter acts as a filter for the resources and it is therefore
entirely appropriate to represent it as an input parameter for the URL.

Google's own URL example (http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=Paris%20Hilton)
can be viewed in this light, provided you view
http://ajax.googleapis.com/ajax/services/search/web as a resource, rather than a remote procedure call.