Understand the concept of Click(object sender, ImageClickEventArgs e)

.aspx page:
============
asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="~/Desert.jpg"
onclick="ImageButton1_Click" />
sapn id= "spannow" runat="server">
.aspx.cs page-
==============
protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
spannow.InnerText += e.X.ToString();
spannow.InnerText += e.Y.ToString();
}