Variables Plugin
The variables plugin allows you to display variables created in the variables module.
You can use a variable in your layouts like this:
{{ variables:variable_slug }}
Example
If you create a variable called twitter_handle, you can display it in your site like this:
Follow us on Twitter at @{{ variables:twitter_handle }}
You can also check the value using an if statement:
{{ if variables:twitter_handle }}We are on Twitter!{{ endif }}
