Rails just keeps on changing. Both Rails 3 and 4, as well as Ruby 1.9 and 2.0, bring hundreds of improvements, including new APIs and substantial performance enhancements. The fourth edition of this award-winning classic has been reorganized and refocused so it's more useful than ever before for developers new to Ruby and Rails. Rails 4 introduces a number of user-facing changes, and the ebook has been updated to match all the latest changes and new best practices in Rails. This includes full support for Ruby 2.0, controller concerns, Russian Doll caching, strong parameters, Turbolinks, new test and bin directory layouts, and much more. Ruby on Rails helps you produce high-quality, beautiful-looking web applications quickly. You concentrate on creating the application, and Rails takes care of the details. Tens of thousands of developers have used this award-winning book to learn Rails. It's a broad, far-reaching tutorial and reference that's recommended by the Rails core team. If you're new to Rails, you'll get step-by-step guidance. If you're an experienced developer, this book will give you the comprehensive, insider information you need. Rails has evolved over the years, and this book has evolved along with it. We still start with a step-by-step walkthrough of building a real application, and in-depth chapters look at the built-in Rails features. This edition now gives new Ruby and Rails users more information on the Ruby language and takes more time to explain key concepts throughout. Best practices on how to apply Rails continue to change, and this edition keeps up. Examples use Concerns, Russian Doll caching, and Turbolinks, and the book focuses throughout on the right way to use Rails. Additionally, this edition now works on Ruby 2.0, a new release of Ruby with substantial functional and performance improvements. This edition is for Rails4.0 and beyond.