Markdown vs HTML: when each is the right answer

Markdown and HTML are often discussed as alternatives. They’re not. Markdown is a writer-friendly source format that compiles to HTML. HTML is the universal document-rendering format that browsers, email clients, and most static-site generators ultimately consume. The question isn’t which to pick — it’s which one you should be writing in.

The headline differences

When Markdown wins

• README files, docs, blog posts. The whole point. Read-while-writing, no tag noise, version control diffs cleanly.
• Comments, issues, chat messages. GitHub, Discord, Slack, every modern collaboration tool accepts Markdown. Bold, links, code blocks, lists — universal.
• Static-site generators. Hugo, Jekyll, Next.js MDX, every modern blog engine takes Markdown input.
• Anywhere prose dominates. Markdown is optimised for “text with occasional formatting” — exactly the ratio writers actually need.

When HTML wins

• Anything with complex layout. Multi-column, tables with cell-level styling, custom positioning. Markdown can’t express what CSS expects.
• Production web pages. The browser only renders HTML. Even when your source is Markdown, the deployed page is HTML.
• Email. Most email clients render HTML; very few render Markdown directly. Marketing emails use HTML + inline styles because email clients butcher anything more sophisticated.
• Interactive elements. Forms, scripts, iframes, accessibility attributes (aria-*, role) — HTML-only territory.

The flavours problem

“Markdown” isn’t one specification. Several incompatible flavours exist:

• CommonMark (2014, ongoing) — the standardisation effort. Strict and predictable. The baseline most modern parsers conform to.
• GitHub Flavored Markdown (GFM) — CommonMark plus tables, strikethrough, task lists, autolinks. The de facto standard for developer docs.
• Pandoc Markdown — extended for academic and book-length use: footnotes, citations, definition lists, math via LaTeX.
• Original John Gruber Markdown (2004) — underspecified in places. Different parsers handle edge cases differently.

If portability matters, write to CommonMark and avoid flavour-specific extensions.

HTML inside Markdown

Most Markdown parsers let you drop raw HTML inline when Markdown isn’t expressive enough. This is the pragmatic escape valve — keep 95% of your document as Markdown, drop into HTML for the table that needs cell colspans, the iframe embedding a video, the form.

Some parsers (StackOverflow’s, for instance) strip most HTML for security. Check the rendering context before relying on this.

The pragmatic rule

• Writing: Markdown. Always start in Markdown.
• Reading: HTML. The browser/email renders the HTML output of your Markdown.
• Edge cases: drop into HTML inline where needed.
• Email marketing, complex layouts, production web: HTML directly.