Introduction to Socket.IO
Socket.IO is a combination of the client-side JavaScript library and Node.js library used to integrate bidirectional communication between a browser and Node.js backend.
The Socket.IO client-side library is used to create a Socket.IO client whereas the Socket.IO Node.js library is used to create a Socket.IO server. The Socker.IO client and server can communicate with each other bidirectionally. Socket.IO primarily uses WebSocket to achieve bidirectional communication.
The main reason for using the Socket.IO client-side library instead of using the WebSocket API is that WebSocket is a relatively new protocol at the time of writing and not all browsers support the API. If Socket.IO sees that the browser doesn't support WebSocket, then it jumps to one of the other mechanisms, such as Flash sockets, long polling, multipart streaming, iframes, or JSONP polling, to implement bidirectional communication between browsers and servers. Therefore, we can say that Socket.IO is...
