A CGI file, also known as a Common Gateway Interface file, is a computer script file that is used to enhance web server capabilities. It is responsible for generating dynamic content, such as forms, web pages or images on dynamic websites.

In simpler terms, CGI files are used to enable a website to interact with its users in a more dynamic and interactive way, by transmitting data back and forth between the server and the user’s web browser.

CGI files are usually written in programming languages such as Perl or Python, and executed by the web server, each time a user requests for a web page or form. The server processes the script and sends the generated content back to the user’s browser as a HTML page, image or other interactive elements.

CGI files can be used for a wide range of website functions such as uploading files, email processing, e-commerce transactions, search functionality, and more. They are widely used across the internet to provide advanced functionality to websites and make them more user-friendly.

Without CGI files, websites would not be as interactive and dynamic as they are today. This technology has made it possible for websites to be more functional and provide users with a better online experience.

However, CGI files can be vulnerable to security attacks, such as cross-site scripting, that can allow an attacker to gain access to sensitive user data, rendering the website unsafe. Website owners need to ensure that their CGI files are secure and regularly updated in order to ensure the safety of users’ data.

In conclusion, as websites continue to evolve, the role of CGI files will become increasingly important. They are responsible for providing essential functionality to websites, and without them, the modern-day internet experience would be dramatically different.