可视元素称为 Web 窗体页。该页面由包含静态 HTML 服务器控件或 ASP.NET 服务器控件（或同时包含这两种控件）的文件构成。在此示例中的窗体页由以下代码组成：
<%@ Page Language="C#" AutoEventWireup="true" Codebehind="Default.aspx.cs" Inherits="PageController._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
Name:<asp:TextBox ID="name" runat="server" />
<p />
<asp:Button ID="MyButton" Text="Click Here" OnClick="SubmitBtn_Click" runat="server" />
<p />
<span id="mySpan" runat="server"></span>
</form>
</body>
</html>
Web 窗体页的逻辑由为了与窗体进行交互而创建的代码构成。编程逻辑放在一个与用户界面文件分离的文件中。此文件被称为"代码隐藏"文件：
using System;
using System.Web;
using System.Web.UI;
namespace PageController
{
public partial class _Default : System.Web.UI.Page
{
protected void SubmitBtn_Click(object sender, EventArgs e)
{
mySpan.InnerHtml = "Hello, " + name.Text + ".";
}
}
}
该类提供可由派生类覆盖的默认实现。
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace PageController
{
public partial class BasePage : Page
{
protected Label eMail;
protected Label siteName;
override protected void OnInit(EventArgs e)
{
//
this.Load += new System.EventHandler(this.Page_Load);
base.OnInit(e);
}
protected void Page_Load(object sender, System.EventArgs e)
{
if (!IsPostBack)
{
string name = Context.User.Identity.Name;
eMail.Text = DatabaseGateway.RetrieveAddress(name);
siteName.Text = "my cool site";
PageLoadEvent(sender, e);
}
}
// this method can be overridden by sub class.
virtual protected void PageLoadEvent(object sender, System.EventArgs e)
{
}
}
}