Why are comments in HTML/CSS so infrequently used? [closed]

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I apologise in advance if this question is asked too often, but I've been doing light web development lately and noticed this across many different (and somewhat prominent) webpages.

I see comments (of varying quality) being used in "more traditional" programming languages, but it's very, very uncommon for me to see them utilised in HTML or CSS. (I've seen it more in JavaScript, though.) I can usually figure out what's going on since HTML isn't very complicated, but why is this so?

Thanks!

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Perhaps the commented version is kept locally, and minified/gzipped versions are the ones shown to the public. This makes loading times faster than those with the additional commentary.

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I think because HTML (and CSS for the most part) is simple markup and rarely contains any complex logic in it (JavaScript maybe). So the markup itself is self-explanatory and requires no additional comments to explain/clarify what it is or what it does.

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The pages you look at the internet are just the end products. Bandwidth costs money and noone wants to pay for sending noticies of the inner workings of their site to visitors most ofwhom never takes a look at the page source.

The backend which generates these pages (as most of the web pages are generated) can have comments of course. There are security concerns too, you don't want to give out unnecessary information about the inner workings of your site.

There are sepcialized tools too just to remove unnecessary content from pages (and css) to create smaller files.

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I would speculate because HTML is a markup language, and all the content is quite transparent - so not necessary to comment compared with a procedural language where the logic can be complex, and a hint helps you to understand it.

I would also speculate it is because a large portion of the HTML is repetitive between pages and sites, so needs no explanation as it has been seen many times before.

You would not want to end up with this would you :)

<h1>My great site</h1>
<!-- heading level one - 'My great site' -->

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Comments are best used to explain tricky bits of a file, and there's not a lot that's tricky about HTML or CSS.

WIth that said, if i'm doing something that works in some specific browser, i'll add a comment about why it's done the way it is. I'll often also use a comment to add notes about bug fixes (especially if there's a ticket for the bug and double-especially if there's a hundred other people working on the CSS as well). But often for HTML, it's almost no effort to turn the HTML comment into a comment in the server-side language, hiding it from the browser completely. So the code could be commented, without you ever knowing it.

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I personally don't use them because during web development, comments tend to be personalized, especially ones you would put into HTML. Instead, I put them in PHP in HTML to make them invisible to the source reader.

As for CSS comments, the only time I have those is when I have over 5000 lines of CSS code and need to separate it into sections. Even then, I prefer to make several smaller files which are self-explanatory through file location and file name, rather than use extensive commenting.

I believe HTML and CSS to be simple and descriptive enough for anyone to derive their meaning very fast without help from comments.

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CSS, especially, is incredibly self-describing. E.g.

margin: 0;

There’s not a lot to add to that. In CSS, I always try to add comments when the purpose of some code isn’t immediately obvious, e.g.

overflow: hidden; /* Contains descendant floats */

And in HTML, I try to make class names and id values self-describing, like good class, method and variable names in programming languages.

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The most important reason for that is as you stated, there is no such a huge need for comments in HTML and CSS.

Secondly, commenting in HTML is very difficult compared to programming languages, putting a <!-- --> mark needs time, whereas // comes from inside.

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Quite simply, HTML and CSS don't need as many comments. For the most part, the CSS and HTML you write does exactly what it says. While it is certainly possible to obfuscate HTML and CSS (especially CSS), it does not happen nearly as often as it does with programming languages. In programming, you need comments because the code is not always self-explanatory and you often do strange things for non-obvious reasons.

Commenting in HTML is only needed when you are doing strange things you neeed to explain. Otherwise, it is just as ridiculous as making comments for code that has an obvious behavior, like this:

var i = 3; //Declares a variable called i and assigns its value to 3.

Example of why you might need a comment in HTML:

<td>&nbsp;</td> <!--IE does not display borders on cells without content-->

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I would assume that it is

1. because HTML is not a programming language and you usually do not have to explain why/how something works..
2. and also because people try to minimize the size of their pages..