An ASPX file is an Active Server Page Extended file used by Microsoft's ASP.NET framework. These files are designed to create dynamic web pages and web applications. They contain scripts and source codes that help communicate to a browser how a web page should be opened and displayed².

Opening and Editing ASPX Files

To open an ASPX file, you can use a web browser or a text editor. For example, you can open it with Notepad++ or Visual Studio. Visual Studio is particularly useful as it allows you to edit and save the file in various formats such as HTML, ASP, and others².

Here is an example of what the source code in an ASPX file might look like:

Configuring Default Page in ASP.NET Core