Below is example of a Timer control. We can use timer control in AJAX. We take a example of datetime how to display time.

Html code for webpage:-
< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
< html XMLNS="http://www.w3.org/1999/xhtml" >
< head runat="server" >
< title >Untitled Page< /title >
< /head >
< body >
< form id="form1" runat="server" >
< div >
< ASP:ScriptManager ID="ScriptManager1" runat="server" >
< /asp:ScriptManager >
< /div >
< asp:UPDATEPANEL ID="UpdatePanel1" runat="server" >
< ContentTemplate >
< asp:Label ID="Label1" runat="server" > < /asp:Label >
< /ContentTemplate >
< Triggers >
< asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" / >
< /Triggers >
< /asp:UpdatePanel >
< asp:Timer ID="Timer1" runat="server" ontick="Timer1_Tick1" Interval="60" >
< /asp:Timer >
< /form >
< /body >
< /html >

Code Behind Form is as Below:-
using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Timer1_Tick1(object sender, EventArgs e)
{
Label1.Text = System.DateTime.Now.ToString();
}
}