According to rubyonrails.org
"Rails is a full-stack framework for developing database-backed web applications according to the Model-View-Control pattern. From the Ajax in the view, to the request and response in the controller, to the domain model wrapping the database, Rails gives you a pure-Ruby development environment. To go live, all you need to add is a database and a web server."
A good tutorial for basic learning of ROR can be found at http://www.onlamp.com/pub/a/onlamp/2005/01/20/rails.html