Chapter 1. Overview of AJAX

AJAX has definitely been the hot buzzword in the Web application world for the last few years. AJAX is an acronym for Asynchronous JavaScript and XML and, in Web application development, it signifies the capability to build applications that make use of the XMLHttpRequest object.

The creation and inclusion of the XMLHttpRequest object in JavaScript and the fact that most upper-level browsers support it led to the creation of the AJAX model. AJAX applications, although they have been around for a few years, gained popularity after Google released a number of notable, AJAX-enabled applications such as Google Maps and Google Suggest. These applications demonstrated to the world the real value of AJAX, and every developer that saw these applications in action immediately went out to do research in how these applications were built.

AJAX is now an out-of-the-box feature of ASP.NET 3.5, and every ASP.NET application that you build is AJAX-enabled by default. This means that you don't have to create a separate AJAX project for your Web applications as the standard projects in Visual Studio for Web application development will already be enabled to use ASP.NET AJAX. This is one of the main new features of ASP.NET 3.5 because of the power that AJAX brings to your applications. The AJAX capability has become so popular since the release of ASP.NET 3.5 that most ASP.NET applications built today make use of at least some features provided by this technology.