Building a modern Web application is challenging. With all the options online, the bar for compelling Web experiences is continually rising: visuals need to be more impressive. Functionality needs to be more complex. And having a differentiated experience that attracts and retains customers is more important than ever.

The technical challenge of creating such a Web application is significant. On one hand, you need a technology that is powerful enough to support your visual goals, be it 3-D, complex animations, or enhanced typography. On the other hand, that same technology needs to enable your application logic. If you choose a solution that relies on the server, users suffer the latency of post back communication. If you instead use a client side implementation, you face the obstacle of developing in a scripting language.

Many times the above technical challenges are already solved on the desktop version of the application. However, online versions have difficulty leveraging desktop solutions because they need to be authored in a Web technology.

Windows Presentation Foundation (formerly code-named "Avalon"), part of the WinFX offerings, provides support for two application types: standalone applications and Web Browser Applications (WBAs). Web Browser Applications, pronounced "wuba," are online-only applications that run in the browser and are not installed. These applications execute in a security sandbox and harness the power of the Windows Presentation Foundation platform for the Web.

This paper discusses the potential of WPF in the browser, the technologies behind Web Browser Applications, and how you might migrate your existing sites. It is targeted at people in the Web space who are interested in enhancing their browser-based experiences.