Google covers best practices for expanding your site to new languages or country-based language variations. We discuss use cases of international sites, implementation of rel=”alternate” hreflang, and best practices.
Webmaster Help Center article on rel=”alternate” hreflang and hreflang=”x-default”:
https://support.google.com/webmasters…
Working with multilingual sites:
http://googlewebmastercentral.blogspo…
Working with multiregional sites:
http://googlewebmastercentral.blogspo…
New markup for multilingual content:
http://googlewebmastercentral.blogspo…
Introducing “x-default hreflang” for international landing pages:
http://googlewebmastercentral.blogspo…
Webmaster discussion forum FAQ on internationalization:
https://sites.google.com/site/webmast…
Webmaster discussion forum for internationalization:
http://productforums.google.com/forum…