The document provides an introduction to Backbone.js in the context of using it with Rails, emphasizing its importance for professional development and maintaining employability. It discusses the structure and functionalities Backbone.js offers, such as models, collections, views, and routers, and provides a step-by-step guide for setting up a Rails application integrated with Backbone.js. The document wraps up by highlighting the benefits of using a client-side MVC framework, including improved code organization and user experience.