When talking about web communications, the server and the browser must adhere to a series of rules. One of these rules is accomplished through HTTP headers. These headers are pieces of information that are exchanged between the server and the client and ultimately regulate and optimize communication processes.
One of the less commonly known headers is the pragma header. This header is mostly used in communications that occur within browsers and in the past had many applications but is now replaced by newer headers.
The usual use of pragma is more for caching control. For instance, "Pragma: no-cache" tells the browser not to use cache and to send a fresh request to the server.
However, it should be noted that pragma is mostly used in a direction that is less commonly used, and instead of it, the "Cache-Control" header is used more effectively for more common usage and better control over the caching processes.
Example Code
GET /index.html HTTP/1.1
Host: www.example.com
Pragma: no-cache
Step-by-Step Explanation of the Code
GET /index.html HTTP/1.1
This line requests a web page named index.html from the server using HTTP/1.1, which indicates the version of the protocol.
Host: www.example.com
In this line, the domain name that the request is being sent to is indicated. For example, in this case, the server is www.example.com.
Pragma: no-cache
This line tells the browser not to use the cache and to fetch a fresh page from the server.