HTML comments tags can also be generated by various HTML software programs. As a rule, let these tags stay, to help support the software that created them. For example, FrontPage and Expression Web might wrap HTML comments with something like:
The purpose for looking at these comment versions is to help you to recognize the <!-- and the --> tags. They are the author's notes, and not really intended for you to read, or even know about. Just be aware that you can use them if you need to!