<!--This is a comment in html.-->
<!--You can put comments enywhere! It does not care if it is mid peice of
code in a peice of code! You must put the ending arrows in or it will
think everything is a comment! Note you can comment over multiple lines.
Use a ! at the start arrow, this may not make sence as the rest of
html uses tags where ! is at the ends.-->

<!-- short comment -->
<!-- loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong comment -->
<!--
multiple
line
comment
-->
<!-- Comments won't be shown on the page or effect the code but will remain in website code. Useful for commenting what is the code for -->

Insert a single-line, or multi-line comment.
Comments are designated by the tags <! -- and -->
Use the comment function to hide scripts on unsupported browsers
. If you are programming in JavaScript or VBScript,
you can use the comment function to hide the script on browsers
that don't support it. Insert the comment at the start of the
script, and end it with //--> to ensure that the script works
on browsers that do support it.

<! –– and the comment closes with ––>

#You need mix html comments tag and ruby comments tag :
'#' and '<!-- -->'

If you want to make a comment in html, you do this
<!-- This is a comment --> This is outside the comment
This is useful if you want to make notes in your code:
<a href="https://www.google.com">Google</a> <!-- This link sends the user to Google -->

<!-- questo è un commento -->

<!-- your Comment inside these tags -->

<!-- das ist ein Kommentar-Tag -->

<!-- Write your Comment Here -->

<!-- here is how to use comment in html -->