ASP.NET is a web application framework developed and marketed by Microsoft. It is used to create dynamic web pages, web services, and web applications. It is an open source server-side web application framework that is designed for web development to produce dynamic web pages. It is built on the Common Language Runtime (CLR), allowing developers to write ASP.NET code using any supported .NET language.

Example:

The following example shows a simple ASP.NET page that displays a message to the user:

Hello World!

This is my first ASP.NET page.