Socket.IO is a JavaScript library that provides you with the ability to implement real-time analytics, binary streaming, instant messaging, and document collaboration. It has two parts: a client-side library that runs in the browser, and a server-side library for node.js. Socket.IO is event-driven and primarily uses the WebSocket protocol that allows us to emit data bi-directionally from the server and the client. Socket.IO This book is a complete resource, covering topics from webSocket security to scaling the server-side of a Socket.IO application and everything in between. This book will provide real-world examples of how secure bi-directional, full-duplex connections that can be created using Socket.IO for different environments. It will also explain how the connection vulnerabilities can be resolved for large numbers of users and huge amounts of data/messages. By the end of the book, you will be a competent Socket.IO developer. With the help of the examples and real-world solutions,you will learn to create fast, scalable, and dynamic real-time apps by creating efficient messaging systems between the server side and the client side using Socket.IO.