Markdown cheatsheet · Highlight
How to highlight text in markdown
Standard markdown has no highlighter. Two extensions cover most tools: ==double equals== where the editor supports it, and the HTML <mark> tag where it does not.
==Double equals== (Obsidian and friends)
Wrap text in two equals signs on each side. Supporting editors render it as a <mark> element, the HTML equivalent of a highlighter stroke.
==The key point== of the meeting.
The key point of the meeting.
This works in Obsidian, iA Writer, and tools built on the markdown-it parser with the markdown-it-mark plugin enabled. It is not part of CommonMark or GFM: paste the same line into a GitHub README and you get literal equals signs.
== spaced out == stays literal even in editors that support the syntax.The <mark> tag (GitHub and most HTML-friendly renderers)
Markdown passes inline HTML through wherever the renderer allows it, and GitHub's sanitizer keeps <mark> on its allowlist. So this version works in READMEs, issues, pull requests and comments, and in any other renderer that does not strip HTML.
This is <mark>the key point</mark>.
This is the key point.
Because it is plain HTML, it also survives conversion to HTML untouched.
When neither works
Some pipelines strip inline HTML and do not know the == extension either. There is no third trick; fall back to bold, the one emphasis every renderer agrees on. See the bold and italic guide.
Common questions
Can I change the highlight color?
Not in the markdown itself; the renderer decides. Browsers give <mark> a yellow background by default, and apps restyle it (Obsidian themes often do). On GitHub, inline style attributes are stripped during sanitization, so <mark style="..."> keeps the tag but loses the color.
Is == coming to standard markdown?
There is no sign of it. Highlighting has been discussed on the CommonMark forum for years without entering the spec, so treat == as a tool-specific convenience, not something portable.