There are many ways you can use comments, and just about every language for the web allows you to use comments. But some people don't like comments because they add download time to the page. But comments can help you maintain your website by reminding you what various blocks of code, CSS, HTML, or whatever do 12 months after you wrote it. Where do you use comments?
Regarding the use of comments.
I use comments a lot in programming. (I’m not talking about websites development here, but the same principles could apply.). I use them to give visual structure to my coding. Even if no-one else sees my code, it helps me to have logical structure to my coding. I can visually separate my code into main-sections, sub-sections, sub-sub-sections, etc., with comments also describing the purpose of each section. For me, it helps with clear thinking, and helps in tracing any bugs.