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Presenting your URLs without the technology ending (i.e. html) is definitely preferable for numerous reasons. This question is frequently asked and I really should write an article on this topic. A couple examples as to why it is preferable: the .html offers no value to consumers and makes your URLs longer the .html lets the bad guys know what type of technology was used to create your pages the .html means that when you change your site to .php pages (a very common change) or any other technology, you will need to 301 your entire site which would lead to a loss of your link equity you worked so hard to build.