This document discusses using React with Rails to add interactivity and improve performance over traditional Rails development with full page refreshes. It explains that React uses reusable components with immutable data to render views, and integrates well with Rails by allowing components to be rendered on the server for SEO. The react-rails gem handles mounting React components and cleaning up references to prevent memory leaks when used with Turbolinks. Overall React is presented as a good solution for progressive enhancement of Rails applications with JavaScript.