Indexing Bilingual Sites

I have a site that supports two languages. The way the user changes the开发者_开发问答 language is by clicking on a language link that will change his session language from A to B and return him to the same page. The problem that I am facing is that Google doesn't index the other language since it is seeing that the language link is the same as the page link but with changes in the parameters.

So is there a way to inform google of the language, or should I add the language in the url, i.e. www.example.com/A/home?

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I think that a good option is to embed the language inside the url like

www.example.com/en/
www.example.com/de/
www.example.com/fr/
etc.

you can also use subdomains like en.example.com but it should be more complex to handle.

Of course you should provide your index page www.example.com all the links to open the sublanguages pages..