What is Ruby on Rails?

Ruby on Rails (or simply Rails) is an open-source web application framework written in the Ruby programming language. It follows the Model-View-Controller (MVC) architectural pattern and is built around two core principles: Convention over Configuration (CoC) — sensible defaults mean you write less code, and Don't Repeat Yourself (DRY) — every piece of knowledge should have a single authoritative representation. Rails emphasizes rapid development and is used to build applications like GitHub, Shopify, Basecamp, and Airbnb.