Markdown

Markdown is a lightweight markup syntax created by John Gruber, designed so the source reads naturally without rendering. Its ubiquity comes from that property: it is legible in a terminal, diffable in version control, and convertible to almost anything.

Its weakness was ambiguity — the original had no specification and implementations disagreed. CommonMark fixed that, and most dialects are now extensions on top of it: tables, footnotes, task lists, and so on. MDX goes further and allows components to be embedded, which turns a document into something closer to a template.

Two authoring points are worth stating.

Fenced code blocks are delimited by a run of backticks, and a closing run must be at least as long as the opening one. That makes any system splicing untrusted text into markdown a correctness problem: content containing a long backtick run must be fenced with a longer one, and any truncation that re-closes a fence has to know the original width. A closing fence shorter than its opening is inert, and one unterminated block swallows everything after it.

Wrapping is the editor's job. Hard-wrapping paragraphs at a column turns every edit into a re-wrap diff; one paragraph per line keeps diffs meaningful.