Page method is a static special method in ASP.NET page code behind. Using page method is an easy way to reduce post backs in your web page. In order to use Page method, you need to follow these steps: 1. In your ASP.NET web page, add the following line inside form tag <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true"> 2. Inside your ASP.NET web page code behind, define a public static method as page method: [ WebMethod ()] public static string [] GetList( string [] arrList) { string [] arrNewList = new string [arrList.Length + 1]; for ( int i = 0; i < arrNewList.Length; i++) { arrNewList[i] = "Item " + i; } return arrNewList; } 3. In your aspx file, add the javascript event handler for the control's client onclick or onchange events. <script type= "text/javascript" language= "javascript" > var ddlControl; function InvokePa...