CGI (Common Gateway Interface) is a standard for running external programs from a Web server. CGI allows the returned HTML page to be dynamic - for example, with a CGI script you could access information in a database and format the results as part of an HTML page. Not surprisingly, CGI scripts are very popular and used extensively throughout the World Wide Web.
There are a number of very good introduction to CGI documents available on the Web. The information given below is a summary of the most important points to remember when using CGI.
Ada's Introduction to CGI - a useful introduction.
Key points to bear in mind when using CGI scripts:
The pre installed scripts available through CPanel are the easiest to use, but if a certain script does not do exactly what you want, feel free to look for better scripts on the Web. You can usually find a script to do almost anything, especially if you are prepared to pay.
Read all available documentation on a particular script before using it. This will help avoid most problems.
CHMOD ("Change Mode") means change the permissions on a particular file (usually the script itself). The CPanel File Manager allows you to quickly do this, as do most FTP tools.
Important - after uploading cgi-bin scripts, CHMOD to 755 (unless the script documentation specifically states otherwise). For example, you need to CHMOD the pre-installed CPanel CGI EMail scripts to 755 to use them properly.
Many scripts need to know the path to Perl (scripting language engine) and to sendmail (HTTP mail engine). You can find this information on the front page of CPanel.
Make sure you test your scripts repeatedly! Testing is vital to make sure everything is working to your satisfaction.