text/markdowntext/markdown is the media type for Markdown documents (RFC 7763). It is plain-text markup that expresses formatting with light symbols (#, *, `), widely used for READMEs, docs, blog drafts, and issue comments.
RFC 7763 defines an optional `variant` parameter to indicate the Markdown dialect (e.g. `text/markdown; variant=GFM` for GitHub Flavored Markdown). Markdown has several dialects — CommonMark, GFM, MultiMarkdown — that differ in support for tables, checkboxes, and footnotes, so declaring the variant helps achieve correct rendering.
Browsers do not auto-render Markdown; they usually show it as plain text or download it. To display it nicely, the server or client must convert it to HTML. When rendering user-authored Markdown to HTML, dialects that allow raw HTML let `<script>` slip in and become XSS, so sanitize the output with a tool like DOMPurify after conversion.
e.g. Content-Type: text/markdown; charset=utf-8