ASP.NET Custom Controls

public class Hello : System.Web.UI.WebControl
{
    public override Render(HtmlTextWriter writer)
    {
        writer.Write("Hello World");
        base.Render(writer);
    }
}

<%@ Register TagPrefix="Example" Namespace="CustomControls" Assembly = "CustomControls" %>

<%@ Register Assembly="NAME_OF_THE_ASSEMBLY" Namespace="NAMESPACE_OF_THE_CUSTOM_CONTROL" TagPrefix="cc1" %>

<cc1:mycustompanel id="MyCustomPanel1" runat="server"><asp:TextBox id="TextBox1" runat="server"></asp:TextBox></cc1:mycustompanel>

<%@ Register TagPrefix="Example" Namespace="CustomControls" Assembly="CustomControls" %>