Based on the Gist by: jcasimir -> https://gist.github.com/jcasimir/1209730#friendly-urls !!
By default, Rails app's build URL based on the primary key (the id) column of the database.
Imagine we have a User model and associated controller. Our first User is called John Doe and has an id = 1. The Url of his user page would be:
/user/1