It is an entirely new more modern web development model and each web application consists of web pages.
It is completely object-oriented programming model, which includes event-driven, control-based architectures that encourages code encapsulation and reuse.
It is support code behind .Net languages like Visual Basic, C#, J#, and many other languages that have third party compilers
It is also a platform for building web services, which are reusable business code that other applications can call across platform and computer boundaries.
You can use a web service to do everything from web-enabling desktop application to share data with a Java client running on UNIX System.
In ADO.NET, a fine tuned data access model and flexible data caching to further boost performance
The other features which include enhanced State Management, Practical Data binding, dynamic graphics, and a robust security model