What is Markdown?
A lightweight plain-text formatting syntax that converts deterministically to HTML, created in 2004 to be readable as source and as rendered output.
Markdown uses punctuation that already looks like formatting in plain text: # heading, **bold**, _italic_, - list, > quote, ` code `. A renderer parses those conventions and emits the equivalent HTML. The result is a format you can read in a terminal, write in any text editor, and render anywhere.
For LLMs and AI pipelines specifically, Markdown is the preferred document format. It's denser than HTML (no tag overhead), preserves structure (headings, lists, tables) that vanilla text loses, and is what most models were trained on. Most modern scraping APIs default to returning Markdown rather than HTML for that reason.
GitHub Flavored Markdown (GFM) added tables, task lists, autolinks, and fenced code blocks; CommonMark stabilized the spec. Almost every Markdown parser in 2026 supports both.
In the wild
# Title→<h1>Title</h1>[Context.dev](https://www.context.dev)→ an anchorjs\nconst x = 1;\n