What Is the Purpose of Hypertext Transfer Protocol?

The hypertext transfer protocol, abbreviated HTTP, is a system by which computers talk to each other across the World Wide Web. It's used by computers and smart phones to ask web servers to send the contents of websites and to submit data through online forms. HTTP is text-based, and it's designed to be readable by humans as well as machines.

The name hypertext transfer protocol refers to HTTP's role in transmitting website data across the internet. Hypertext refers to the standard form of websites in which one page can refer users to another page through clickable hyperlinks, usually simply called links. The purpose of the HTTP protocol is to provide a standard way for web browsers and servers to talk to each other.

Web pages are designed using the hypertext markup language, or HTML, but HTTP is used today to transfer more than simply HTML and the cascading style sheets, or CSS, used to indicate how pages should be displayed. HTTP is also used to transfer other content on websites including images, video and audio files.

Computers can connect to web servers using HTTP simply to request the files at particular web addresses, such as http://www.example.com/folder/file.html or to submit data through web forms. When a computer is simply fetching data, it usually sends an HTTP message called a GET request, and when it's sending form data or uploading a file it uses other formats of messages called PUT or POST requests. You can see the HTTP messages your web browser is sending in many browsers through the built-in developer tools.

Today, HTTP is used by many applications other than web browsers to send messages to servers. People creating applications choose HTTP on purpose because it's well understood by many developers and partly because HTTP is typically unfiltered by network firewalls designed to allow web traffic, meaning that HTTP messages can get through without a problem on most home and business networks.

In some cases, you may notice that a web address begins with HTTPS rather than simply HTTP. HTTPS refers to hypertext transfer protocol secure and, as the name suggests, is a more secure variant of HTTP.

Specifically, it opens an encrypted connection between the web browser and server so that data can be sent encoded in a way that won't be readable by eavesdroppers. By contrast, HTTP messages and data are sent as plain text, so anyone who is able to observe your connection, whether through a shared Wi-Fi network or by connecting to a computer between your computer and the web server, can read your messages.

Shopping sites and apps, as well as others that require credit card information or handle personal correspondence, such as email or instant messages, almost invariably use HTTPS.