/cgi-bin is the directory where most "CGI (Common Gateway Interface)" scripts reside. CGI is a standard that allows the web-server to execute a separate program in order to generate content. For example, the URL http://www.example.com/cgi-bin/homepage.pl?user=rob runs the program "homepage.pl" in order to generate content specific to the user "rob". All "interactive" web sites, as well as e-commerce sites, use some form of scripting to produce their output. Many of these are written specifically for each web site, or by people who then give them away. While the chance is low that any particular script can be exploited by a hacker, the huge diversity in scripts means that thousands of them are out there that can be exploited.
