A web server is a program that runs continuously on a computer, waiting for execution requests from a client or an Internet user.
The web server is responsible for responding to these requests appropriately, delivering as a result a web page or information of all kinds according to the requested commands. This exchange is mediated by the browser and the server talking to each other using HTTP. Various technologies can be used on the server to increase its power beyond its ability to deliver HTML pages; these include CGI scripts, SSL security, and Active Server Pages (ASP).
A basic web server has a very simple operating scheme, based on infinitely executing the following loop:
1. It waits for requests on the indicated TCP port (the default standard for HTTP is 80).
2. Receive a request.
3. Find the resource.
4. It sends the resource using the same connection through which it received the request.
5. Go back to the second point.
When we browse the Internet, we are continually accessing hundreds of Web servers, which are repositories of information in the form of Web pages, arranged for rapid delivery.
Information storage can be done on a “dedicated server”, a server computer dedicated exclusively to the client’s site (for high-demand applications), or on a “shared server”, which means that the same server (computer + program served) will be used for multiple clients sharing the resources.