Prior to Visual Studio 2008, the ASP.NET AJAX product was a separate installation that you were required to install on your machine and the Web server that you were working with. This release gained in popularity quite rapidly and is now a part of the Visual Studio 2008 offering. Not only is it a part of the Visual Studio 2008 IDE but the ASP.NET AJAX product is also baked into the .NET Framework 3.5. This means that to use ASP.NET AJAX, you don't need to install anything if you are working with ASP.NET 3.5.
If you are using an ASP.NET version that is prior to the ASP.NET 3.5 release, then you need to visit www.asp.net/AJAX to get the components required to work with AJAX.
ASP.NET AJAX is now just part of the ASP.NET Framework. When you create a new Web application, you do not have to create a separate type of ASP.NET application. Instead, all ASP.NET applications that you create are now AJAX-enabled.
If you have already worked with ASP.NET AJAX prior to this 3.5 release, you will find that there is really nothing new to learn. The entire technology is seamlessly integrated into the overall development experience.
To sum up what AJAX is all about in relation to ASP.NET in a simple phrase, it would be "an improved experience for the end user through partial page updates and a better user interface." At the core of the ASP.NET AJAX offering is the UpdatePanel control (introduced in this chapter), which provides the capability to have portions ...