Interaction: Common Gateway Interface (CGI)

Why?

Need for dynamic Web sites

update of the information on the web site required "on the fly" (i.e. dynamically)
e.g. News, Meteorology

need some real interaction with the user: dealing with the forms filled in by the user
e.g. the obvious one: a search engine

CGI is a standard specifying a means for external programs to interface with information servers

When the web server runs a CGI program, it collects the program's output and returns it to the web browser. Thus, the browser receives information which has been dynamically generated.