What Are WebSockets? A Brief Introduction
WebSockets make it possible to have interactive, two-way communication sessions between the user's browser and a server.
In this short video tutorial I'll take a moment to explain WebSockets. We won't go into the low-level details of WebSockets, but it helps to understand what's going on behind the scenes. I'll also give you an overview of the current browser support for WebSockets.
Watch the Tutorial
Watch the Full Course
WebSockets are a powerful and efficient tool for building interactive websites. In the full course, Connect the Web With WebSockets, I'll show you how to build a real-time link-sharing application that uses Express and Socket.IO.
Source: Tuts Plus