jsp support two type comment : JSP comment and HTML comment

JSP Comment:

<%-- comment text --%>

this is the format of the JSP comments specified in the JSP Specifications. A JSP Comment is removed by the JSP Engine at the translation time itself and the compilation unit doesn't contain them. Comments don't need to ne compiled as we all know that they are not executed and they simply serve the purpose of making the source code more readable, and maintainable.

HTML Comment:

<!-- comment text -->

this is the syntax of an HTML comment as specified by the HTML Specifications. A JSP page considers this as a normal HTML tag and hence it doesn't remove them. All HTML comments are maintained in the response and one can easily see them jusy by viewing the page source of the rendered HTML page in the browser.

jsp scriptlet tag also support java comment and these comments are treated the same way they are treated in a normal Java program.They all are removed before compilation and like JSP Comments they are also not part of the compilation unit.It defined as:

<%
        String name;  
        // java comment

       /*
         multiple 
         line
         java 
         comment 
       */

    %>