HTTP status codes are standard response codes given by web site servers on the internet.
The codes help identify the cause of the problem when a web page or other resource does not load properly.
HTTP is the protocol used to transfer data between the web server and browsers. The server respond to a browser by providing a HTTP response header.
Server headers response are the informations, in the form of a text record, that a Web server sends back to a client's browser in response to receiving an HTTP request.
The response header contains the date, size and type of file that the server is sending back to the client and also data about the server itself.