The guide provides a comprehensive walkthrough for building a real-time commenting system using React, Node.js, and Socket.io, demonstrating how to set up a list of comments fed from an API, create new comments, and broadcast them in real-time to users. It begins by establishing the project's structure, creating a Node.js API server with Express.js, and implementing basic HTTP endpoints using static and in-memory data. The guide then details how to develop the React front-end application using create-react-app, build various React components, and integrate Socket.io for real-time communication between the client and server. Additionally, it introduces Knock, a developer platform for constructing cross-channel notification systems, highlighting its capabilities for sending notifications to in-app and out-of-app channels like email and Slack through a single API call. The system is designed to be scalable and efficient, allowing for real-time user interaction and notification management.