Templated User Controls "Container" Keyword

I'm working with Templated User Control's. In the final markup of the control, the data is being accessed by the Container keyword. I'm using the word 'keyword' freely, because I do not understand whether this is a keyword, or where the Container word is coming from. Below is an example from my book.

//Address User Control markup
<%@ Control Language="C#" AutoEventWireup="true"
CodeFile="AddressUcTemplated.ascx.cs" Inherits="AddressUcTemplated" %>
<asp:PlaceHolder runat="server"
ID="PlaceHolderAddressTemplate">
</asp:PlaceHolder>
--
//Address User Control code-behind
public partial class AddressUcTemplated :
System.Web.UI.UserControl
{
protected void Page_Init(object sender, EventArgs e)
{
//clear the controls from the placeholder
PlaceHolderAddressTemplate.Controls.Clear();
if (LayoutTemplate == null)
{
PlaceHolderAddressTemplate.Controls.Add(
new LiteralControl("No template defined."));
}
else
{
AddressUcContainer container = new
AddressUcContainer(this.Address);
this.LayoutTemplate.InstantiateIn(container);
//add the controls to the placeholder
PlaceHolderAddressTemplate.Controls.Add(container);
}
}
[PersistenceMode(PersistenceMode.InnerProperty)]
[TemplateContainer(typeof(AddressUcContainer))]
public ITemplate LayoutTemplate { get; set; }
public Address Address { get; set; }
}
--
//Naming Container Class
public class AddressUcContainer : Control, INamingContainer
{
public AddressUcContainer(Address address)
{
this.Address = address;
}
public Address Address { get; set; }
}
--
//Page using the user control; the Container keyword is confusing me in the below //statement
...
<%@ Register src="AddressUcTemplated.ascx" tagname="AddressUcTemplated"
tagprefix="uc1" %>
<uc1:AddressUcTemplated ID="AddressUcTemplated1"
runat="server" AddressType="Home">
<LayoutTemplate>
<h1>Edit Home Address</h1>
<table>
<tr>
<td>Address Line 1:</td>
<td>
<asp:TextBox ID="TextBoxAddress" runat="server"
Text="<%#Container.Address.AddressLine1%>"></asp:TextBox>
...