In yet another SEO Snippets video John Mueller of Google addresses another basic SEO question, around how you end your URLs, what extension you use.
The question was "will removing that HTML from our URLs help my site?" The answer is no, it doesn't matter either way.
John said:
URLs are important for search engines like Google. Do they care which endings your URLs use though? The answer is no.
But if you change URLs, that can matter. John said:
Google uses URLs to identify pieces of content. Whether your URLs end with .html, .php, .asp or just have words in them, doesn't really matter to Google. All of these URLs can show up in search in the same way. That's it.If you need to change your URLs, for example if you move to a new content management system that doesn't allow you to use .html URLs at all, keep in mind that this change would be a restructuring of your website. You would need to redirect the old URLs to the new ones. This kind of change can take quite a bit of time to be reprocessed. So picking a time when you're not dependent on search is a good idea. And because it can take time we don't recommend doing this kind of change on a wim. When making URL changes pick URLs that you're sure can last a longer period of time.
Here is the video:
Forum discussion at Twitter.