Over the past two decades, Rails has taken countless companies to millions of users and billions in market valuations. Over six thousand people have contributed code to Rails, and many more have served the community through evangelism, documentation, and bug reports. Rendering HTML templates, updating databases, sending and receiving emails, maintaining live pages via WebSockets, enqueuing jobs for asynchronous work, storing uploads in the cloud, providing solid security protections for common attacks. Databases come to life with business logic encapsulated in rich objects. Modeling associations between tables, providing callbacks when saved, encrypting sensitive data seamlessly, and expressing SQL queries beautifully. Controllers expose the domain model to the web, process incoming parameters, set caching headers, and render templates, responding with either HTML or JSON.