Markdown is not one language. It is a family. The original 2004 spec was vague enough that every parser invented its own dialect; CommonMark fixed that, then GFM and MDX extended it.

CommonMark

CommonMark is the de facto strict baseline. Every modern parser starts here.

Heading
bold italic code
[link](https://example.com)
list item

> quote

If your content needs to portably render across many tools, target CommonMark.

GitHub Flavored Markdown (GFM)

GFM adds the features developers actually want:

• Tables
• Task lists - [x] done
• Strikethrough ~~text~~
• Autolinks for URLs
• Fenced code with language hints
• Footnotes

If you write for GitHub, GitLab, or any developer documentation site, GFM is the lingua franca.

MDX

MDX lets you embed JSX inside Markdown:

My Post
import Chart from './Chart';
Regular markdown continues here.

Used by Docusaurus, Next.js content, Astro. Powerful for interactive documentation; harder to author and review than plain Markdown.

Other Flavors

• Pandoc Markdown — academic features (citations, math)
• Asciidoctor — separate language often confused with Markdown
• DokuWiki, MediaWiki — wiki-specific syntaxes

Math Support

GFM does not support math. CommonMark does not support math. For LaTeX-style equations, use:

$$

E = mc^2
$$

via remark-math or KaTeX. Many platforms (GitHub, Notion) added this on top.

Picking a Flavor

• Public docs site → MDX or GFM
• README files → GFM
• Static blog → GFM is the safe default
• Research notes with math → Pandoc

Use the [Markdown Editor](https://sdk.is/markdown-editor) for live preview.