When the server runs the script, the script is no longer the stuff you typed up, it now becomes a thing in memory space. That means, if you make infiniteloop.pl and run it, and delete the file, the thing will keep going and going.. and going... So.. You see, each "run" of the script, is actually a "copy" .. or an 'instance'.

You may want to look at the lovely CGI::Session, sounds like you'll head there at some point.