## TL;DR

Rails (David Heinemeier Hansson, 2004) is a convention-over-configuration web framework in Ruby. It popularized MVC in web development, RESTful routing, database migrations, and scaffolding. Rails 7 (2021) introduced Hotwire (Turbo + Stimulus) for reactive UIs without heavy JavaScript.

## Core Explanation

Conventions: model file name maps to table name, controller actions map to URL patterns. ActiveRecord: ORM with migrations, validations, associations (has_many, belongs_to). Scaffold generates CRUD: `rails generate scaffold Post title:string body:text`. Asset Pipeline (Sprockets) and Webpacker for frontend. Turbo: replaces Rails UJS — faster page updates without full reload.

## Further Reading

- [Ruby on Rails Guides](https://guides.rubyonrails.org/)