<asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="~/asp-net.jpg"Width="91px"/>

It has same event as in Button but having different properties

Properties

When you click on a imagebutton then click event will fire.

You can provide an event handler for the Click event to programmatically control the actions performed when the image button is clicked.

<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
protected void Button1_Click(object sender, EventArgs e)
    {
         Label1.Text = "Hello";
    }

Here, when you click theimage Button then it will display message “Hello” in Label1