Hypertext transfer protocol (HTTP) is a communications protocol that transfers information on intranets and the World Wide Web to retrieve and publish hypertext pages. While most people are familiar with HTTP because it is at the beginning of every web URL, many do not know why it is there. The hypertext transfer protocol is in place to send out the message that a particular web browser is looking for the particular web page at the address that follows the HTTP in the address bar of the web browser window. Yet the actual process of HTTP and the request it makes is much more complicated than what any visitor to a website actually sees.
When the HTTP goes out, it is a response or request protocol between a client and a server to access a certain resource, which may be a web page or other graphic stored in the server as files. The client can be a number of things, such as a web browser, a search engine spider, or any other end-user tool, while the server is a storage area for a particular set of HTML files and images. The user agent, as the client is called, uses the hypertext transfer protocol to communicate with the server, which is also called the origin server. Between the user agent and the origin server there may also be many intermediary processes such as proxies, gateways, and tunnels, all of which work together to finish the transfer of information to the end user. The HTTP request sends a URL to the server for a file (a web page, an image, or another type of file) stored there. The URL is then sent back to the end user.
Of course, the simplistic way of looking at hypertext transfer protocols is certainly a good way to learn how they work, but there is much more to HTTP than simply sending the message that an end user wants to see a web page. HTTP actually identifies eight different methods which indicate what the desired action is and what action should be performed. These eight different methods are:
HEAD – Asks for the material in a GET request, but without the response body.
GET – Requests the representation of a specified source with a response body.
POST – Submits the data to be processed from an HTML form to the identified source.
PUT – Uploads a representation of the source that has been specified.
DELETE – Deletes a specific source.
TRACE – This echoes back a specific request so that the user can see what servers are adding or changing the request.
OPTIONS – Used the check the functionality of a web server by returning the HTTP methods that the server supports for a specified URL.
CONNECT – Facilitates SSL-encrypted communication through an unencrypted HTTP proxy by converting the request connection to a transparent TCP/IP tunnel.
Important to communication and the way the entire Internet works, the hypertext transfer protocol or HTTP is a necessary protocol.