After last time on WordPress permalinks, I’ve questioned appending the .html to the end of posts. So, I did an exhaustive research of the matter.
Granted, the .html is faux in nature. These aren’t static html pages, we’re just adding it to help improve search engine ranks.
The appending of html does a few things:
1) Prevents /my-article/ and /my-article from being viewed as different pages. Bloggers are only going to do .html… since bloggers know not to touch that. This makes the canonical URL forced… nobody can even consider a link other than the one the URL originated from.
2) Encourages not linking to comments. /my-article.html#comments stands out more than /my-article/#comments (in other words, bloggers are more likely to chop off the #comments, and link to the root, .html article). However, search engines may be less likely to view it as the same page (they may see /#comments as being root of the trailing article, but see .html and .html#comments as different), so it is a bit of a double-edged sword.
3) Pages can be made static down the road, in case you want to change platforms in the future. Of course, you’d have to go through and use some sort of script to do this, but then you can keep the articles where they stand.
Reason #1 has been diminished significantly by Google. Google deployed a technology internally called BigDaddy, which tends to these minor un-canonicalities. Reason #2 is a toss-up. Reason #3 is the one that becomes the winner.
Having transitioned from PHP-Nuke, to Joomla, to WordPress… PhoneNews.com has been a huge loser in the search engine ranking business. The switch to WordPress should end that, but nobody can forsee the future of SEO. We may have to change platforms over there, and that holds even more true for my own blog (since, I’ll probably be writing on here much longer than on PhoneNews.com, it is my personal blog after all).
In the end, should you add .html? That’s up to you, you need to ask yourself how important SEO is for a site, and if your existing structure already needs changing. Since I was already having to change permalink structure… it made sense to toss .html into the mix at the same time.