In our first tutorial we wrote a Perl program to read a file with a number in it, add one to that number, and then write it back out to the file. We installed it on the server and then ran it. This was all done on the server, but what about the internet?

We did use the internet for tutorial one. We used it to ftp the program and data file to the server, and while using telnet to run on the server. What we didn't do was use the web, not at all. In fact everything we did in lesson one could have been done before the world wide web was even invented!

Ok, then what was the point to lesson one? We set up a count file, but it will only count when we get on telnet and run it. What we are going to do today is set things up so that it counts hits for a webpage. In other words we'll change the program, and also set up a webpage on our server which executes the program. Once that's done, the counter will increment every time the webpage gets downloaded from the server.

This is CGI programming, and the technique we will use to implement this CGI application will be server side includes, or SSI.