One of the key features of .NET 3.5 is that it fosters separation of the user interface layer from the business and persistence layers. Since the UI layer is, by definition, the most visible layer and is often subject to the greatest scrutiny by customers, Microsoft has traditionally offered a spectrum of options to developers for this layer.
With .NET 3.5, developers have the ability to create multiple types of applications, including server-side-only (ASP.NET), thin-client (ASP.NET with AJAX), rich interactive (Silverlight), traditional desktop (WinForms), and rich desktop (WPF) applications.
While AJAX has not officially been put into the .NET 3.5 bucket, it is a key component of Microsoft’s overall approach of offering a unified set of tools that foster well-designed programs that meet customers’ needs. Thus, we have decided that any comprehensive coverage of the .NET 3.5 technologies must include Microsoft’s AJAX libraries as well.
Get ready for ASP.NET applications that perform faster, from the user’s point of view—much faster.
A key point that I have emphasized in every edition of my book Programming ASP.NET (O’Reilly) is that ASP.NET is a server-based technology. Traditionally, whatever you saw in your browser was (almost) exclusively produced on the server; (nearly) all the code was run on the server, and (just about) all the HTML that came to the browser came from the server ...