Rails is the most popular web frameworks built on Ruby.Rails uses the Model-View-Controller (MVC) architecture pattern to organize application programming.
Ruby on Rails features several tools intended to make commonplace development tasks easier "out of the box". Rails provides scaffolding which can automatically construct some of the models and views needed for a basic website. A simple ruby web server (WEBrick) and Rake build system are also included. By including these common tools with the Rails framework, a basic development environment is in effect provided with all versions of the software.
Ruby on Rails relies on a web server to run it. Mongrel is generally preferred over WEBrick at the time of writing but it can also be run by Lighttpd, Apache (either as a module - Passenger for example - or via CGI, FastCGI or mod_ruby), and many others.
Rails is also noteworthy for its extensive use of JavaScript libraries Prototype and Script.aculo.us for Ajax. Rails initially utilized lightweight SOAP for web services; this was later replaced by RESTful web services.
Since version 2.0, Ruby on Rails by default offers both HTML and XML as output formats. The latter is the facility for RESTful web services.
