This document provides an overview of Ruby on Rails, an open-source web application framework written in Ruby. It was created in 2004 by David Heinemeier Hansson and has grown increasingly popular since. The framework aims to make developing web applications simpler and more enjoyable by making things like databases, sessions, and routing intuitive. It includes several internal components that handle common development tasks like ActiveRecord for ORM, ActionPack for handling controllers and views, and more.