How to Comment a Markdown File

Markdown doesn't include specific syntax for comments, but there is a workaround using the reference style links syntax. Using this syntax, the comments will not be output to the resulting HTML.

Here are a few examples:

[]: # (This is a comment)
[]: # "And this is a comment"
[]: # 'Also this is a comment'
[//]: # (Yet another comment)
[comment]: # (Still another comment)

Each of these lines works the same way:

• [...]: identifies a reference link (that won't be used in the article)
• # defines the destination, in this case # is the shortest valid value for a URL
• (...), "...", and '...'define the reference title, which we repurpose to make a comment

While this is the best approach that I'm aware of, it doesn't allow multi-line comments and each comment must appear on it's own line.

I personally prefer to use [//]: # since, as a software developer, I tend to associate // with comment syntax.

Adding HTML Comments in Markdown

If you'd like for your comments to show up in the HTML output, a simple modified HTML comment syntax will work:

<!--- This is an HTML comment in Markdown -->

Unlike a "normal" HTML comment which opens with <!-- (two dashes), an HTML comment in Markdown opens with <!--- (three dashes). Some Markdown parsers support two-dash HTML comments, but the three-dash version is more universally compatible.

Broader Topics Related to Markdown Code Comments

Markdown

Knowledge about Markdown