CGI Definition CGI has two different meanings: 1) Common Gateway Interface, and 2) Computer Generated Imagery. 1) Common Gateway Interface The Common Gateway Interface (CGI) is a set of rules for running scripts and programs on a Web server. It specifies what information is communicated between the Web server and clients' Web browsers and how the information is transmitted. Most Web servers include a cgi-bin directory in the root folder of each website on the server. Any scri...