The HTML server controls are basically the original HTML controls but enhanced to enable server side processing. The HTML controls like the header tags, anchor tags and input elements are not processed by the server but sent to the browser for display.
They are specifically converted to a server control by adding the attribute
runat="server"
and adding an
id
attribute to make them available for server-side processing.
For example, consider the HTML input control:
<input type="text" size="40"></input>
It could be converted to a server control, by adding the runat and id attribute:
<input type="text" id="testtext" size="40" runat="server"></input>
Please check this link
http://www.w3schools.com/aspnet/aspnet_refhtmlcontrols.asp