What is an AP file?
An AP file is an Active Web Page that runs on a web server and is used to create dynamic web pages. These web pages are then served to the requesting browser and displayed to user. AP file consist of HTML and JavaScript code that is executed on the server. Being more generic, AP files use .ap extension instead of the conventional server side .php or .asp extensions.
AP File Format - More Information
AP files are hosted on the Web server with the help of supporting software. It is then executed on the server and the response is sent back to web browser for display or further processing.