TCP/IP Application

Most of the times Node.js is used for HTTP-based servers. There are times however when you need to go one level deeper, and write your software based on TCP/IP protocol instead of HTTP. Indeed, HTTP was originally designed as a request-response protocol, and it is text-based. TCP/IP is more "raw": it is binary (meaning, more effective) and also it is full-duplex persistent connectinon (which again means it is more effective). If you are building an application that is not targeted specifically at browsers, there's a good chance that TCP/IP will be a better choice to you than HTTP.