You are coding away on an ASP.NET page, and are trying to isolate a problem within the page. You have some existing html/controls/markup/in-line code that is being used on the page, and you want to temporarily comment it out while you fix the problem. ASP.NET supports a little known feature called “server-side comments” that you can use to completely disable code/controls/html in a page. Server-side comments in ASP.NET are delimited using a <%-- --%> syntax. For example:
<%--
Commented out HTML/CODE/Markup. Anything with
this block will not be parsed/handled by ASP.NET.
<asp:Calendar runat="server"></asp:Calendar>
<%# Eval("SomeProperty") %>
--%>
The key difference between client-side HTML comments and server-side comments is that with client-side comments code/controls will still be executed on the server. With server-side comments, the ASP.NET compiler will ignore everything whithin these blocks.