Ruby on Rails - often called RoR, or just Rails, is an open source web application framework written in Ruby that closely follows the Model-View-Controller (MVC) architecture.
It strives for simplicity and allowing real-world applications to be developed in less code than other frameworks and with a minimum of configuration. Rails has gained a reputation for being a sustainable, enjoyable way to develop web applications

Ruby on Rails is defined as a full-stack framework which means that the framework supports everything necessary to build web application development (minus the DataBase) under one umbrella.