Store language in cookie or appear on the url?

What is the best practice, to store the language in a cookie or at url?

[Kainourios]

I have a site which is on 8 languages. I'd like to ask what is the prefered method to switch the languages, with cookie or in the url (for example www.example.com/en/page/ or www.example.com/page.php?locale=en)? What are the advantages and the disadvantages of each method? Has any SEO problems by storing it on cookie?

Thank you

[Receptional]

Not the easiest question to answer, but here's my best practice... Although opinions may vary.

1: put each language in it's own directory /en, /fr etc.
2: put language preference in cookie BUT
3: ensure google and users alike can spider/navigate from the home page (and anywhere) to all languages without cookies. And
4: use Webmastertools to help google with region settings.

To be honest, though, there are other considerations as well. If your TLD is a country code, you'll have issues anyway in search. Another option is subdomains rather than subdirectories.

But in answer to your question, I'll choose cookies.