#Internationalization or "I18n"

##Internationalization Basics
i18n—short for "internationalization." (There are 18 letters between the "i" and the "n" in "internationalization.") Internationalization means architecting and developing an application in order to bring support for a second locale—possibly at a future time. 

The default tool for internationalizing a rails application is with the ruby i18n gem. 

Basically, the i18n gem creates a directory called config/locales. Rails then stores the application's various languages in a yaml file, such as en.yml for English or fr.yml for French.

The I18n gem ships with a feature called variable interpolation that allows you to use variables in translation definitions and pass the values for these variables to the translation method.

 Example en.yml file:

    en:
      hello_world: "Hello world"
      hello: "Hello %{name}"