Poking Software

First, some background: CGI, URL, HTTP, HTML

Basically, a URL is:  protocol://server/filepath/

Examples:
http://www.google.com/
ftp://ftp.openbsd.org/pub/OpenBSD/3.7/
telnet://m-net.arbornet.org/

port, user/password are other options

URLs are a key to the lock.