What is CGI?
What is CGI? CGI stands for Common Gateway Interface. This is not to be confused with another CGI which stands for Computer Generated Imagery which is the technology they use for special effects and explosions of the things in major motion pictures.
This CGI the common gateway interface. It is a technology that allows the web browsers submit forms and interact with programs on the web server.
So when you see a web form of any kind and you fill it and when you press the submit button then it goes, what happens from this point is CGI, the web browsers submits the data to the server, the server passes this data onto an application, the application responds and then it goes back up to the chain that your web browser and web browser gets some kind of result and may be something happens at the back-end and like the database thing or sending an email or something that sort of thing.
CGI is used for simple interactive applications. For complicated applications like Google Maps, Gmail or something like that use another technology called Ajax which sometimes actually uses CGI on the back and to communicate with the application on the server.
But CGI is used for simple interactive applications. CGI applications can be written in any programming language. The most common ones are the languages like Python, PHP and things like that, that tend to be simple languages. Because CGI application tends to be simple applications, for this reason CGI applications are often called “CGI Scripts”. Because the languages that they are written in tend to be what are called Scripting languages, they tend to be very simple languages and for this reason they are often called as “CGI Scripts”.
Off course they can be written in any programming language sometimes more complex languages like ASP or Java or even C++, can be used.
But it is important to note that CGI applications run in the server, they do not run in the web browser. So the technology that’s used by the CGI application must be supported by the web server. And the requirements for running the applications on server and the security restrictions and things like that must all be followed according to the rules of the server, not according to the rules of your local computer or your application.
This is because the CGI applications run on the server and not in the web browser.
That’s what CGI is!