HTTP: The Protocol Every Web Developer Must Know Part 2

In his previous article, Pavan Podila covered some of HTTP’s basics, such as the URL scheme, status codes and request/response headers. With that as our foundation, we will look at the finer aspects of HTTP, like connection handling, authentication and HTTP caching. These topics are fairly extensive, but we’ll cover the most important bits.

A connection must be established between the client and server before they can communicate with each other, and HTTP uses the reliable TCP transport protocol to make this connection. By default, web traffic uses TCP port 80. A TCP stream is broken into IP packets, and it ensures that those packets always arrive in the correct order without fail. HTTP is an application layer protocol over TCP, which is over IP.

HTTPS is a secure version of HTTP, inserting an additional layer between HTTP and TCP called TLS or SSL (Transport Layer Security or Secure Sockets Layer, respectively). HTTPS communicates over port 443 by default, and we will look at HTTPS later in this article.