<!-- opening tag
--> closing tag
OK, now that we’re far enough down on the page, it’s time to include the super-secret, double-special tag: the comment. OK, so James Bond might not be searching for it, but it is pretty useful in HTML. This tag allows you to place comments in your code that are ignored by the web browsing software. You can read them if you look at the raw HTML code, but they don’t display on the screen when the document is viewed in a web browser. Here’s an example:
Use comments to make notes about the contents and structure of a document, especially if someone else will need to work with your HTML code.