What is the HTTP Server header?
HTTP stands for Hypertext Transfer Protocol — the underlying language that lets different kinds of Web software (like browsers and servers) communicate. HTTP headers are small data fields that accompany a Web-based message and help the software that is going to use that message make sense out of it. For example, request a page using an ordinary Web browser and, along with the request itself, a set of request headers will be sent to the server where the page resides.