Allows you to include code comments in the body of an .aspx file. Any content between opening and closing tags of server-side comment elements, whether ASP.NET code or literal text, will not be processed on the server or rendered to the resulting page.
<%-- commented out code or content --%>
ASP.NET server-side comment blocks have the same uses as traditional language-specific comment blocks, including documentation and testing.
Within <script runat="server">
A compilation error will occur if you use server-side comment blocks within <% %> blocks.
The opening and closing comment tags can appear on the same line of code or can be separated by many commented-out lines.
Server-side comment blocks cannot be nested.
The following example demonstrates an HtmlButton control that is commented out.
<%-- <button runat="server" id="MyButton" OnServerClick="MyButton_Click"> Click here for enlightenment! </button> --%>
Introduction to Web Forms Pages | ASP.NET Page Syntax