Markdown Bold, Italic, and Strikethrough Formatting

Markdown bold text uses double asterisks (**), italic uses single asterisks (*), and strikethrough uses double tildes (~~). You can combine all three for bold italic strikethrough text. These are the most basic markdown formatting tools, and they work in every markdown editor, GitHub, Notion, Discord, and most chat platforms.

How to Make Text Bold in Markdown

Wrap your text in double asterisks or double underscores to create markdown bold text.

**This is bold text**
__This is also bold text__

Both produce identical output. However, the asterisk style (**) is more popular. About 94% of markdown files on GitHub use asterisks over underscores for bold, according to a 2023 analysis of public repositories.

Markdown bold works anywhere in a sentence:

The **quick** brown fox jumps over the **lazy** dog.

You can bold entire phrases, single words, or even parts of compound words (though mid-word bold with underscores can fail in some parsers). Stick with asterisks for consistent results.

When to Use Bold

Bold text draws attention. Use it for:

• Key terms when first introduced
• UI labels ("Click Save to continue")
• Warnings or important notices
• Table headers or list item labels

Don't overuse markdown bold. If everything is bold, nothing stands out. A good rule: no more than 10% of your text should be bold.

How to Italicize Text in Markdown

Wrap text in single asterisks or single underscores for markdown italic.

*This is italic text*
_This is also italic text_

Again, both produce the same HTML output (<em> tags). Asterisks are the preferred convention. The CommonMark spec treats them identically, but underscores can behave unexpectedly mid-word in some parsers.

Markdown italic is useful for:

• Book, article, and film titles
• Technical terms on first use
• Emphasis within a sentence
• Placeholder text in syntax examples

Read *The Pragmatic Programmer* for practical advice.
Replace *your-username* with your actual GitHub handle.

About 68% of README files on GitHub contain at least one italic element, typically for emphasis or term definitions.

Markdown Bold Italic (Combined)

Use triple asterisks for markdown bold italic text. This combines both styles in one.

***This is bold and italic***
___This also works___
**_Mixed syntax works too_**
*__And this combination__*

All four lines produce the same result. The cleanest approach is triple asterisks (***). Mixed syntax (like **_text_**) works but is harder to read in source files.

Bold italic is rare in practice. Use it sparingly for maximum impact, such as critical warnings or key definitions.

Strikethrough in Markdown

Markdown strikethrough uses double tildes. This isn't part of the original markdown specification; it's a GitHub-flavored markdown extension.

~~This text is crossed out~~

Strikethrough is useful for:

• Showing corrections: "The meeting is at 3 PM 4 PM."
• Indicating deprecated features in documentation
• Crossing off completed items in informal lists
• Humorous or rhetorical effect in casual writing

Not every markdown parser supports strikethrough. The editors that do include GitHub, GitLab, Reddit, Discord, Notion, and most modern markdown tools. Standard CommonMark doesn't include it, though many CommonMark-based parsers add it as an extension.

Combining Bold, Italic, and Strikethrough

You can mix all markdown formatting styles in a single block of text.

This is **bold**, this is *italic*, and this is ~~struck~~.
You can even do ***bold italic*** with ~~**bold strikethrough**~~.

Here's a quick reference table for all combinations:

Style	Syntax	Output
Bold	**text**	text
Italic	*text*	text
Bold Italic	***text***	text
Strikethrough	~~text~~	text
Bold Strikethrough	~~**text**~~	text
Italic Strikethrough	~~*text*~~	text
All three	~~***text***~~	text

Nesting order matters in some parsers. If a combination doesn't render correctly, try changing the order of the markers.

Asterisks vs Underscores: Which Should You Use?

Both * and _ work for markdown bold and italic, but asterisks are the safer choice. Here's why:

1. Mid-word formatting: un*frigging*believable works with asterisks. un_frigging_believable may not parse correctly in some flavors.
2. Consistency: Asterisks work for bold, italic, and bold italic without switching characters.
3. Convention: The vast majority of style guides (including Google's markdown style guide) recommend asterisks.

My recommendation: use * for italic, ** for bold, *** for bold italic. Save underscores for filenames and variables.

Platform Differences for Markdown Formatting

Markdown formatting works slightly differently across platforms. Here's what to expect:

Platform	Bold	Italic	Strikethrough
GitHub	** and __	* and _	~~
Reddit	**	*	~~
Discord	**	*	~~
Slack	*bold* (different!)	_italic_	~strike~
Notion	**	*	~~
Stack Overflow	**	*	Not supported

Slack is the notable outlier. It uses single asterisks for bold and single underscores for italic, which is the opposite of standard markdown. Keep this in mind if you switch between platforms.

Testing Your Markdown Formatting

The fastest way to test markdown bold, italic, and strikethrough is to paste your text into a live preview editor. Our online editor renders formatting in real time, so you can see exactly how your text will look.

For documents that need to be shared as files, use the MD to PDF converter to export formatted output. You can also convert to HTML with the MD to HTML tool for embedding in web pages.

Need to clean up inconsistent formatting? The formatter tool standardizes your markdown syntax and fixes common issues.

Markdown bold, italic, and strikethrough are the building blocks of text formatting. Stick with asterisks for consistency, combine styles when you need extra emphasis, and test your formatting in a live editor before publishing. For the full syntax reference, check the markdown cheat sheet.