Google does not read or use the content within your HTML comments for Google Search or ranking purposes. Google's John Mueller confirmed this once again saying, "Googlebot doesn't understand your HTML comments."
John said this on Reddit after he was asked about putting content in the HTML comments so that Google can read that content, since the website was lacking content in general.
Here was the question:
Hey, hello everyone! There is an idea and I need your opinion. I will come in from afar, on my site text recognition from a picture works (that is, the user sees a picture on the site and text from the picture below it), and it does not always recognize everything correctly. The idea arose to write an HTML comment to the Google bot before the text, something like "the text that was recognized in such tool and such a way, do not judge strictly" xD, this is just an example. In general, this comment can be written in different ways, I am curious about the possible downsides in this situation.
It goes back to Google saying that you should put content on your pages, not just in your images.
John Mueller replied:
That's a bold plan, but no. Googlebot doesn't understand your HTML comments. You wouldn't believe what people have put into HTML comments. Oh my.
This is not new, we covered that Google ignores links in HTML comments a few years ago.
Forum discussion at Reddit.
