Ajax Control Toolkit AutoComplete
AutoComplete extends any ASP.NET TextBox control. It associates that control with a popup panel to display words that begin with the prefix that is entered into the text box. When the user has entered more characters than a specified minimum length, a popup
displays words or phrases that start with that value. By default, the list of words is positioned at the bottom left side of the text box.
The candidate words that match the user input are supplied by a Web service. Caching is enabled, so if the same characters are entered multiple times, only one call is made to the Web service.
Enter the text "Star" into the following TextBox: