How to register assembly for AjaxControlToolkit?

In order to register assembly for AjaxControlToolkit, we need to follow few basic steps.
 1. First of all, download and install AjaxControlToolkit.
 Please follow the link to download @
 For Installation, @
 2. Make the following updates in web.config file.
 i) Under assemblies tag, add following AjaxControlToolkit assembly
 <add assembly="AjaxControlToolkit, Version=3.5.60919.0, Culture=neutral,
 ii) Under controls tag, add following
 <add tagPrefix="aspext" namespace="AjaxControlToolkit" assembly="AjaxControlToolkit,
 Version=3.5.60919.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e"/>
 Note: Please make sure to change the AjaxControlToolkit version in above entries.
 3. Now simply place the toolkit controls on your pages in much the same way we normally place other web controls.
 <aspext:DropDownExtender ID="popupdropdown" runat="server"
 DropDownControlID="pnlGrid" TargetControlID="txtSuggestedAppointment">
 In this simple tutorial, I register AjaxControlToolkit to an application but hopefully it will work for registering any control library to your applications.