CodeIgniter is an open-source PHP framework that follows the MVC architecture (Model–View–Controller).
Its main advantage is being simpler and lighter than Zend or Symfony, with a fast learning curve.

• Tutorial 1: CodeIgniter internationalization

  We detail in this first tutorial the internalization by language files in the version 2.1.3 of this framework: how to set up language files, how to load them in controllers, then how to display their variables in views, while managing their parameterization and the question of variables order.

Professional CodeIgniter Thomas Myer Wrox

CodeIgniter for Rapid PHP Application Development David Upton Packt Publishing

• Tutoriel 2: SEO-friendly localized URLs with CodeIgniter

  This second tutorial explains how to create localized SEO-friendly URLs, i.e. understandable URLs for both search engines and users.

• Tutoriel 3: How to extend a CodeIgniter helper

  This third tutorial explains how to extend a helper, which means how to add new functions to that generis toolkits to better suit it to yout application needs. We will see more precisely how to add the support of another language (here, French) to the plural function of the inflector helper, and thus enabling the pluralization of French.