Language support and multilingual sites
Internet search engines usually take care of language support in terms of language determination and language specific processing.
The language information need not be carried in the URLs itself, nor in language specific metadata in the HTML source of the respective page. In most cases it is good practice to encode the content of pages by using UTF-8 encoding.
If the site is a multilingual site, then enable the web crawlers to get to the content in the various languages through links. Enabling language switching or selection based on either the cookie of a returning customer or using JavaScript to switch from one language to the other, will lock out web crawlers. Therefore in such a case the crawler picks up the content in the default language only. You can also check the webmaster recommendations published by the internet search providers for further details and suggestions.