What is Common Gateway Interface (CGI)?

The Common Gateway Interface (CGI) is a standard protocol that allows web servers to interact with external programs, enabling dynamic content generation. When a user submits a form or requests a script, the web server uses CGI to execute a corresponding application, such as a Python, Perl, or PHP script. This application processes input (e.g., form data), generates output (e.g., HTML), and sends it back to the server, which forwards it to the user’s browser. CGI scripts are commonly stored in a designated directory like /cgi-bin. While versatile, CGI can be resource-intensive, leading to the adoption of modern alternatives like APIs.