I know that there is probably no definitive answer, but
does it matter in search engine optimization whether you use PHP or ASP for your CMS.

Look forward to hearing your ideas.

There is no difference at all. Search engines don't care what server-side language you use. They only see the HTML they produce.

There is an absolutely definitive answer: search engines see pages. Search engines do not see the code that produces pages.

I remember the day when "web developers" first concerned themselves about oh, performance, database connectivity, effeciency, code reuse... now we worry about search engine "optimization" before even learning the most fundamental first principles of web development, such as the difference between "client" and "server".

This is sad.

Slightly OT, one thing you might consider is that search engines don't tend to carry results like http://www.example.com/products.php?category=5&id=6. Instead, you might want to use something like mod_rewrite (if you use Apache) and have your links point to http://www.example.com/products/5/6 instead, and have mod_rewrite re-write it to the original URL. That's a negative effect of these scripting languages. Back to the original question, it then doesn't matter what language you use, as the search engine won't even know you're using php (well, they can find out under normal config, but you can disable things like that too (php.ini expose_php setting)).

That's simply not true. Bots can follow parameterized links just fine. Nor do they have access to configuration files. I'm sure you mean well, but spreading "SEO" rumors and mis-information is not helpful.

I disagree! Nearly all bots can follow paramaterized links just fine. However, they are aware that they are dynamic URLs and are often much more reluctant to include them. MCP was right in stating that "search engines don't tend to carry results like" ... he said nothing about having a problem following them.

Based on what evidence? I know you use mod_rewrite here, but I don't on my forum, and when I do a targeted search for specific pages, there isn't an issue finding them. I think this is one of the great myths of SEO.

Search engines will index any page that has a query string with the she same results as a page without a query string. The only time a query string will cause SEO issues is if it contains a session ID or id= in the query string (because that can be perceived as a session ID). Otherwise there is no difference between the two as far as getting pages indexed.

tgreer, it depends on the URL, specifically the types and number of parameters present. stymiee is more correct in this regard. There's a video by Matt Cutts (see http://en.wikipedia.org/wiki/Matt_Cutts for more on who he is) on how Google pageranks dynamic URLs vs static URLs. You can view this here http://video.google.com/videoplay?do...20126300142609

Of course, this is only talks about how Google treats these, and other search engines may use different logic.

My original point was more along the lines that mod_rewrite can help eliminate any bias search engine logic may weigh against dynamic URLs. I can't see how it can hurt anyhow.

(And, for the record, I found this video with that URL through Google and it was the #1 hit.)

Keep in mind, though, that "PageRanks" have very little to do with actual search engine results, the indexing of the pages. All search engines can and do index parameterized URLs, so there should be no excessive hand-wringing in regard to dynamically-generated pages with PHP and/or ASP.