Files with the .ASP extension contain data in the form of code used for generating HTML websites by a server using the right engine. It contains scripts written in script languages accepted by the server, usually VBScript and JScript, as well as HTML and XHTML code. When the browser sends a request to open an ASP page, the Windows server processes it using the Miscrosoft IIS engine – after the server executes the scripts, the browser receives the resulting HTML page.

Currently, and already since 2002, due to the support for more script languages, better effectiveness, the possibility to debug and other new technologies, ASP technology is not used in favor of the ASP.NET environment. ASP.NET page files are characterized by the .ASPX extension.