JSP pages provide two types of comments that we can use:
HTML Comments: Since JSP pages are like HTML, we can use HTML comments like <-- HTML Comment -->. These comments are sent to client also and we can see it in HTML source. So we should avoid any code level comments or debugging comments using HTML comments.
JSP Comments: JSP Comments are written using scriptlets like <%-- JSP Comment --%>. These comments are present in the generated servlet source code and doesn’t sent to client. For any code level or debugging information comments we should use JSP comments.