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Rails is a web-application framework that includes everything needed tocreate database-backed web applications according to theModel-View-Controller (MVC)pattern.

Understanding the MVC pattern is key to understanding Rails. MVC divides yourapplication into three layers: Model, View, and Controller, each with a specific responsibility.

TheModel layer represents the domain model (such as Account, Product,Person, Post, etc.) and encapsulates the business logic specific toyour application. In Rails, database-backed model classes are derived fromActiveRecord::Base.Active Record allows you to present the data fromdatabase rows as objects and embellish these data objects with business logicmethods.Although most Rails models are backed by a database, models can also be ordinaryRuby classes, or Ruby classes that implement a set of interfaces as provided bytheActive Model module.

TheView layer is composed of "templates" that are responsible for providingappropriate representations of your application's resources. Templates cancome in a variety of formats, but most view templates are HTML with embeddedRuby code (ERB files). Views are typically rendered to generate a controller responseor to generate the body of an email. In Rails, View generation is handled byAction View.

TheController layer is responsible for handling incoming HTTP requests andproviding a suitable response. Usually, this means returning HTML, but Rails controllerscan also generate XML, JSON, PDFs, mobile-specific views, and more. Controllers load andmanipulate models, and render view templates in order to generate the appropriate HTTP response.In Rails, incoming requests are routed by Action Dispatch to an appropriate controller, andcontroller classes are derived fromActionController::Base. Action Dispatch and Action Controllerare bundled together inAction Pack.

Active Record,Active Model,Action Pack, andAction View can each be used independently outside Rails.

In addition to that, Rails also comes with:

• Action Mailer, a library to generate and send emails
• Action Mailbox, a library to receive emails within a Rails application
• Active Job, a framework for declaring jobs and making them run on a variety of queuing backends
• Action Cable, a framework to integrate WebSockets with a Rails application
• Active Storage, a library to attach cloud and local files to Rails applications
• Action Text, a library to handle rich text content
• Active Support, a collection of utility classes and standard library extensions that are useful for Rails, and may also be used independently outside Rails

1. Install Rails at the command prompt if you haven't yet:

   $ gem install rails

2. At the command prompt, create a new Rails application:

   $ rails new myapp

   where "myapp" is the application name.

3. Change directory tomyapp and start the web server:

   $cd myapp$ bin/rails server

   Run with--help or-h for options.

4. Go tohttp://localhost:3000 and you'll see the Rails bootscreen with your Rails and Ruby versions.

5. Follow the guidelines to start developing your application. You may findthe following resources handy:

   • Getting Started with Rails
   • Ruby on Rails Guides
   • The API Documentation

We encourage you to contribute to Ruby on Rails! Please check out theContributing to Ruby on Rails guide for guidelines about how to proceed.Join us!

Trying to report a possible security vulnerability in Rails? Pleasecheck out oursecurity policy forguidelines about how to proceed.

Everyone interacting in Rails and its sub-projects' codebases, issue trackers, chat rooms, and mailing lists is expected to follow the Railscode of conduct.

Ruby on Rails is released under theMIT License.