CGI - Common Gateway Interface
Computer Graphics Interface is a standard protocol for running scripts and programs on a Web server. It allow web server to pass information from browser to an external application. Here, an external application is any program designed to accept and return data that conforms to the CGI specification.
One problem that occurs with Common Gateway Interface, a new process is created everytime a CGI request is made. So, it put a lot of load on the server.
How does Common Gateway Interface (CGI) works
When the user requests a webpage from a server, the server sends it to the browser. However, when a user enter his details in the requested web page and submits it, the complete information goes to the server. This information needs to be processed by an application program located in the server itself. This method or convention of passing message between the server and the application program is known as common gateway interface.