.ASPX File Extension

Server-generated Web page that may contain VBScript or C# code; often created with Microsoft Visual Web Developer and is designed for the Microsoft ASP.NET framework; scripts within the page are processed on the Web server and the resulting HTML is sent to the user's Web browser.

ASPX pages are also called ".NET Web forms." They can be identified in a Web browser when the URL in the address field ends in ".aspx".