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Would it be better to create sub-domains for those translations (same content, different language) or sub-folders? You can safely use either method. For the most part it is solely a matter of your preference. Neither choice has a SEO benefit nor disadvantage when compared to the other. If it was my site, I would choose to go with the subdomain approach as a means of separating the content. The site structure would be identical other then the prefix. It would be easiest to manage in my opinion. But who am I? How about listening to Matt Cutt's opinion http://www.mattcutts.com/blog/subdomains-and-subdirectories/