The Microsoft Ajax content delivery network (CDN) enables you to easily use either the Microsoft Ajax Library or jQuery in any web page. For example, you can start using the preview version of the Microsoft Ajax Library simply by adding the following<script> tag to a page that points at ajax.microsoft.com:

    <script src="http://ajax.microsoft.com/ajax/beta/0910/Start.debug.js" type="text/javascript"></script>

View instructions for using the Microsoft Ajax CDN.

Developers familiar with the ASP.NET server-side programming model can take advantage of the ASP.NET AJAX server-side controls such as the ScriptManager, UpdatePanel, and the UpdateProgress control to add AJAX functionality to an ASP.NET application without writing any JavaScript. For example, the UpdatePanel control enables you to update a portion of an ASP.NET page without requiring you to reload the entire page. The ScriptManager control enables you to manage browser history in an AJAX application by updating the browser back button after an AJAX request.

The ASP.NET AJAX server-side controls are included as a standard part of the ASP.NET 3.5 framework. These controls are already in your Visual Studio/Visual Web Developer toolbox. If you are using an earlier version of the ASP.NET framework, such as ASP.NET 2.0, then you can download the ASP.NET AJAX Extensions.

In addition the AJAX Control Toolkit (described below) provides many more controls that you can add to your toolbox and include in your pages.

Learn more about server-side ASP.NET AJAX by watching a video tutorial or reading a written tutorial.

If you prefer to work directly with JavaScript then you can take advantage of client-side ASP.NET AJAX. The client-side ASP.NET AJAX Library provides a foundation for building rich client-side applications. The library simplifies cross-browser development of client-side applications. For example, the library enables you to call web services and create components and controls -- all through pure client-side JavaScript code.

The client-side ASP.NET AJAX Library is included with ASP.NET 3.5. You also can download the standalone Microsoft AJAX Library.

The ASP.NET AJAX Preview on CodePlex contains a preview of the new features coming with the next version of the client-side ASP.NET AJAX framework. The next version of the framework includes many powerful new features including:

• Client-side templates that enable you to render data completely in the browser.
• Declarative instantiation of client-side controls and behaviors.
• Client-side DataView control for creating dynamic data-driven UI.
• Live binding between data and HTML elements or client controls.
• Client-side command bubbling.
• Full integration of WCF and ADO.NET Data Services with client code, including client-side change tracking.

The AJAX Control Toolkit (May 2009 Release) contains more than 30 controls that enable you to easily create rich, interactive web pages. For example, you can use the Toolkit controls to display HTML editors, auto-complete textboxes, cascading dropdown lists, picture slide shows, and modal popup dialog boxes.

You don't need to know JavaScript to use the AJAX Control Toolkit. For example, if you want to add a popup calendar to a TextBox control, you can simply select the Add Extender task option and select the Toolkit Calendar from a dialog box.

The ASP.NET AJAX Control Toolkit is an open-source project that is a joint effort between Microsoft and the ASP.NET AJAX community. You can download the AJAX Control Toolkit from the CodePlex.com website.

To learn more about the AJAX Control Toolkit, you can view and experiment with the AJAX Control Toolkit live. Or, learn more about the Toolkit by watching video tutorials or reading written tutorials.

The jQuery library is a very popular open source JavaScript library that has a passionate and active developer community. jQuery enables you to easily retrieve and manipulate elements from a HTML document by using a selector syntax similar to the syntax used in Cascading Style Sheets. The jQuery library is included as a standard part of Microsoft ASP.NET MVC applications.

Visual Studio 2008 and the free Visual Web Developer Express 2008 provide you with a great development environment for creating AJAX applications. Visual Studio supports Intellisense for JavaScript, and popular JavaScript libraries such as jQuery, so that you get JavaScript statement completion as you type.

Visual Studio and Visual Web Developer also support rich debugging of executing JavaScript applications. You can set breakpoints, inspect objects, and use the immediate window to modify JavaScript at runtime.

Download Visual Web Developer Express from this website and start building rich AJAX applications.