An open-source project ASP.NET AJAX Control Toolkit comes with a useful control called AutoCompleteExtender. This control helps to extend like a dropdown list control behavior (provides a key/value mode) with auto-complete features. For more description about AutoCompleteExtender refer AutoComplete page. This articles will shows how to get values from database using web service, how to apply css styles for list items, use different properties and even how to show a loading image inside extender.