CGI

From HostPedia

CGI stands for the Common Gateway Interface which is a standard protocol for connecting script and applications with a web server. With CGI, a web server can pass client side requests recieved from the user's web browser to the application (or script) on the server and send the output back to the user.

CGI is known mostly for using script files written in scripting languages like Perl, but it is also possible to use executable programs.