WPML stands for WordPress Multilingual and it is a plugin that can make your website multilingual.
They currently power over half million websites and are the industry standard in allowing you to translate themes, plugins, theme options, posts, pages, widgets, custom post types and everything else on WordPress. On top of that they have an amazing support forum.
Their plugin is very flexible with built functions. You can order custom translations from over 50 languages straight from the WordPress dashboard from ICanLocalize.
Here is what you need to know on turning your site multilingual with WPML.
First, you need to to purchase a recent version of WPML, including the String Translation and Translation Management modules.