What does a CDN provide?

Content delivery networks (CDNs) are composed of "edge cache" servers that are strategically placed around the world at key Internet network points. These "edge cache" servers can be used to cache and deliver all types of content – including images, videos, CSS and JavaScript files.

Using a CDN can significantly improve a website's end-user performance, since it enables browsers to more quickly retrieve and download content. For example, instead of having a browser request for an image traverse all the way across the Internet to your web server to download, a CDN can instead serve the request directly from a nearby "edge cache" server that might only be a single network hop away from your customer (making it return much faster – which makes your pages load quicker).

What does the Microsoft AJAX CDN provide?

The Microsoft AJAX CDN makes it really easy to add the jQuery and ASP.NET AJAX script libraries to your web sites, and have them be automatically served from one of our thousands of geo-located edge-cache servers around the world.

For example, if you want to use jQuery from the Microsoft AJAX CDN then you can simply add a standard script tag to your page using the URL below:

   <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.3.2.min.js" type="text/javascript">script>    

When the browser requests the script file it will be automatically served by the CDN "edge cache" server that is closest to the end-user. This means:

* The request will be processed much faster than if it had to hit your web-server (making the end-user's page load much faster)

* You don't have to pay for the bandwidth of this file – since the file comes from our server we pay the bandwidth cost (saving you money)

* The script can be easily cached across multiple web-sites – which means it might not even need to be downloaded if the user has already hit a web-site that requested the file (and as such has it already in the browser's cache).

You can get a full listing of the JavaScript libraries (and associated URLs) we already have loaded in our CDN cache here: www.asp.net/ajax/cdn

We'll update the available libraries in the CDN as we ship new versions of ASP.NET AJAX, and continue to update it to include all of the JavaScript files we ship with ASP.NET and Visual Studio (including jQuery, the jQuery Validation plugin, and additional libraries we ship in the future).

The CDN service is free and available for anyone in the community to use for both commercial and non-commercial purposes. You do not need to register to take advantage of it.
Using the Microsoft AJAX CDN with the ASP.NET 4.0 ScriptManager

In addition to allowing you to reference script files directly using a

<script src="http://ajax.microsoft.com/ajax/beta/0909/MicrosoftAjax.js" type="text/javascript">script>
    <script src="http://ajax.microsoft.com/ajax/beta/0909/MicrosoftAjaxTemplates.js" type="text/javascript">script>