Custom Controls ASP.Net Tutorial

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebControlLibrary1
{
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:WebCustomControl1 runat=server>")]
    public class WebCustomControl1 : WebControl
    {
        private string text;
        private Guid _bookid;
        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        public string Text
        {
            get
            {
                return text;
            }
            set
            {
                text = value;
            }
        }
        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        [TypeConverter(typeof(GuidConverter))]
        public Guid BookId
        {
            get
            {
                return _bookid;
            }
            set
            {
                _bookid = value;
            }
        }
        protected override void Render(HtmlTextWriter output)
        {
            output.RenderBeginTag(HtmlTextWriterTag.Input);
            output.RenderEndTag();
        }
    }
}