Start Here
Everything you need to know to install Rails and create your first application.
Models
This guide will get you started with models, persistence to database and the Active Record pattern and library.
This guide covers how you can use Active Record migrations to alter your database in a structured and organized manner.
This guide covers how you can use Active Record validations
This guide covers how you can use Active Record callbacks.
This guide covers all the associations provided by Active Record.
This guide covers the database query interface provided by Active Record.
Views
This guide provides an introduction to Action View and introduces a few of the more common view helpers.
This guide covers the basic layout features of Action Controller and Action View, including rendering and redirecting, using content_for blocks, and working with partials.
Guide to using built-in Form helpers.
Controllers
This guide covers how controllers work and how they fit into the request cycle in your application. It includes sessions, filters, and cookies, data streaming, and dealing with exceptions raised by a request, among other topics.
This guide covers the user-facing features of Rails routing. If you want to understand how to use routing in your own Rails applications, start here.
Digging Deeper
This guide documents the Ruby core extensions defined in Active Support.
This guide covers how to add internationalization to your applications. Your application will be able to translate content to different languages, change pluralization rules, use correct date formats for each country and so on.
This guide describes how to use Action Mailer to send and receive emails.
This is a rather comprehensive guide to doing both unit and functional tests in Rails. It covers everything from 'What is a test?' to the testing APIs. Enjoy.
This guide describes common security problems in web applications and how to avoid them with Rails.
This guide describes how to debug Rails applications. It covers the different ways of achieving this and how to understand what is happening "behind the scenes" of your code.
This guide covers the basic configuration settings for a Rails application.
This guide covers the command line tools and rake tasks provided by Rails.
Various caching techniques provided by Rails.
This guide documents the asset pipeline.
This guide covers the built-in Ajax/JavaScript functionality of Rails.
This guide explains how to write a mountable engine.
This guide explains the internals of the Rails initialization process as of Rails 3.1
Extending Rails
This guide covers how to build a plugin to extend the functionality of Rails.
This guide covers Rails integration with Rack and interfacing with other Rack components.
This guide covers the process of adding a brand new generator to your extension or providing an alternative to an element of a built-in Rails generator (such as providing alternative test stubs for the scaffold generator).
Contributing to Ruby on Rails
Rails is not 'somebody else's framework.' This guide covers a variety of ways that you can get involved in the ongoing development of Rails.
This guide documents the Ruby on Rails API documentation guidelines.
This guide documents the Ruby on Rails guides guidelines.
Maintenance Policy
What versions of Ruby on Rails are currently supported, and when to expect new versions.
Release Notes
This guide helps in upgrading applications to latest Ruby on Rails versions.
Release notes for Rails 4.0.
Release notes for Rails 3.2.
Release notes for Rails 3.1.
Release notes for Rails 3.0.
Release notes for Rails 2.3.
Release notes for Rails 2.2.
Feedback
You're encouraged to help improve the quality of this guide.
Please contribute if you see any typos or factual errors. To get started, you can read our documentation contributions section.
You may also find incomplete content, or stuff that is not up to date. Please do add any missing documentation for master. Make sure to check Edge Guides first to verify if the issues are already fixed or not on the master branch. Check the Ruby on Rails Guides Guidelines for style and conventions.
If for whatever reason you spot something to fix but cannot patch it yourself, please open an issue.
And last but not least, any kind of discussion regarding Ruby on Rails documentation is very welcome in the rubyonrails-docs mailing list.