Simplifies the creation of mail service classes that uses Action View (from Action Pack) to render the body templates.

Eases web-request routing, handling, and response as a half-way front, half-way page controller. Implemented with specific emphasis on enabling easy unit/integration testing that doesn't require a browser.

Implements the ActiveRecord pattern (Fowler, PoEAA) for ORM. It ties database tables and classes together for business objects, like Customer or Subscription, that can find, save, and destroy themselves without resorting to manual SQL.

Think Active Record for web resources.

Utility classes and extension to the standard library that were required by Rails, but found of general use.

Rails is a web-application framework for the MVC pattern that includes both a template engine, controller framework, and object-relational mapping package. Everything needed to develop web-apps that can run on CGI, FastCGI, and mod_ruby.