What Is CGI?

CGI stands for "Common Gateway Interface". It is a server-based service which provides a means of adding expanded functionality to Web pages over and above what HTML provides. This expanded functionality is provided by using small programs, or "scripts", that are executed on the server the Web page files reside on. When you see that "cgi-bin" appear on the location line, you probably executed a CGI script on the server when you initially loaded the page, or will in the course of using the page.

CGI is utilized by placing an appropriate HTML tag in your HTML document ("Web page"). The author of the script you wish to use should provide you with the appropriate HTML tag needed to run that script. When the page is loaded by a browser, i.e. viewed by a site visitor, the tag "calls" the script and it is executed by the server. Note that this is different from Java applets or JavaScript, which are executed on the client (visitor's) system via their browser.