HTML controls are outwardly identical to plain old HTML 4.0 tags, but employ the runat="server" attribute. For each of HTML’s most common tags, a corresponding server-side HTML control exists, although Microsoft has added a few tags and some extra properties for each. Creating HTML controls is easy—we simply stick a runat="server" attribute on the end of a normal HTML tag to create the HTML control version of that tag. The complete list of current HTML control classes and their associated tags is given in Table 4.1.

These HTML control classes are all contained within the System.Web.UI.HtmlControls namespace.

Because HTML controls are processed on the server side by the ASP.NET runtime, we can easily access their properties through code elsewhere in the page. If you’re familiar with JavaScript, HTML, and CSS, then you’ll know that manipulating text within HTML tags, or even manipulating inline styles within an HTML tag, can be cumbersome and error-prone. HTML controls aim to solve this by allowing you to manipulate the page easily with your choice of .NET language, for instance, using VB.NET or C#. We’ll start by looking at the HTML controls library, then we’ll explore in more detail the properties exposed by the controls when we process a simple form containing HTML controls and code.

<a href="somepage.aspx" runat="server">Click Here</a>

<button id="myButton" OnServerClick="Click" runat="server">Click 
Here</button>

<script runat="server" language="VB">
Sub Click(s As Object, e As EventArgs)
  Response.Write(myButton.ID)
End Sub
</script>

<script runat="server" language="C#">
void Click(Object s, EventArgs e) {
  Response.Write(myButton.ID);
}
</script>