Best practice on URL design of a multi-language site

[Stanimir Stamenkov]

I've wondered if there's a best practice on defining the URL
structure of a multi-language site. I've seen the following
pattern, requesting:

https://addons.mozilla.org/

redirects me to:

https://addons.mozilla.org/en-US/seamonkey/

I suppose the preferred language is initially determined from the
'Accept-Language' request header. Next, wherever I navigate in the
site all URLs start with:

https://addons.mozilla.org/en-US/

e.g.:

https://addons.mozilla.org/en-US/seamonkey/addon/433

When I pass that URL to a person which has different language
preferences he will still be served the English variant which I
rather don't want. Providing URLs serving specific language
variants (e.g. by supplying 'alternate' LINKs in the HEAD of HTML
document) is o.k. but using "default" URLs serving a language
variant depending on the current visitor preferences is more
practical in my opinion.

Given other large sites like http://msdn.microsoft.com/ employ the
same "fixed" language URLs - what do you think is better, having:

http://www.example.net/article

serving the language variant as the current user preference is, or
having it always redirect to:

http://www.example.net/en-US/article

(or the whatever the current user preference is) which serves only
the given language variant?

--
Stanimir