What is a Rails plugin?
A Rails plugin is either an extension or a modification of the core framework. It provides a way for rails developer to share bleeding-edge ideas without hurting the stable code base. We need to decide if our plugin will be potentially shared across different Rails applications.
A plugin creates models, view helpers, controllers, rake tasks, images, style sheets, javascripts, test assertions and unit and functional tests like rails application.
How to create a plugin?