Markdown

A lightweight markup syntax for plain-text documents — # for headings, * or - for lists, [text](url) for links. Designed to be readable as raw text and convertible to HTML.

When you'd see it: Every developer-adjacent tool that handles documentation — GitHub READMEs, Notion, Obsidian, Slack (partially), Discord, static site generators, AI chat interfaces. Also the source format for most reference and documentation sites.

Why it matters: Markdown is the closest thing to a universal authoring format for structured text. Once you can read and write it, you can author for a wider range of tools without learning each tool's bespoke editor.

Common mistakes: Treating Markdown as one standardized language. There are several dialects — CommonMark, GitHub-flavored, Pandoc, others — and features like tables, footnotes, or admonitions vary between them. When a Markdown file doesn't render the way you expect, it's often a dialect mismatch.

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