One of the most common questions I get is this: is it better to file extension php, asp, html, or that do not? Many still argue that the advantage html extension, but it never know for sure though Matt Cutts've said several times that it does not matter, even recently, that file extension is not important at all .
Sometimes at a conference people will ask me "Does it matter what extension I use for my pages? Does Google prefer. Php over. Asp, or. Html over. Htm? And my answer is "We're happy to crawl all of these file extensions. It does not matter what you choose between any of those."
Of course not important until you choose the one extension that search engines do not crawl, or you certainly will not find in the search results. For example, you can read a post on SEOmoz: Unwritten Google Webmaster Guideline: Do not End URLs in .0 . I knew I encounter sites that have "classic" extension as well as most, but some of his or differently than most. This course is no problem if you do not just happen to accidentally select the extension that search engines do not crawl. So before you start creating your URLs to make sure that your pages with the extension already in the index of search engines, unless you choose a different extension if you expect something from the search engines.
Web 2.0 notion of where and who often writes a lot of demand is an excellent example of how easy it is automatically "fall out" from the index, because if you have rewritejtane links without slash at the end of the term and at the end of the search engines it looks like the file extension .0. Little things that may later cause a lot of headaches.
