This is a sample configuration for deploying Ruby on Rails applications.
See http://www.talkingquickly.co.uk/2014/01/deploying-rails-apps-to-a-vps-with-capistrano-v3/ for a tutorial on usage.
Or for more details, this is also the example configuration used in the book Reliably Deploying Rails Applications available on Leanpub: https://leanpub.com/deploying_rails_applications