Using Button and Grideview Export to Microsoft Excel Format

Question

Export to Microsoft Excel Format

please explain this code

 protected void Buttonexp_Click(object sender, EventArgs e)

        {

            Response.Clear();

            Response.AddHeader("content-disposition", "attachment;filename=GridView_to_Excel.xls");

            Response.Charset = "";

            Response.ContentType = "application/vnd.xls";

            StringWriter StringWriter = new System.IO.StringWriter();

            HtmlTextWriter HtmlTextWriter = new HtmlTextWriter(StringWriter);

            GridView1.RenderControl(HtmlTextWriter);

            Response.Write(StringWriter.ToString());

            Response.End();

    }

        public override void VerifyRenderingInServerForm(Control control)

        {

        }