MD - Markdown

Markdown is a way of writing formatted text in a plain text file. Instead of buttons and hidden codes, you type a few ordinary characters, and a Markdown program turns them into headings, emphasis, lists and links. Markdown files usually end in .md, sometimes .markdown.

John Gruber created Markdown in 2004, with Aaron Swartz, and published it on his website Daring Fireball together with a small Perl script that converted it to HTML. His goal was a format that is easy to read before it is converted: a Markdown file should look like a tidy plain text email, not like code.

The syntax in brief

• # Heading makes a heading; ## Heading a smaller one, down to six levels.
• *emphasis* or _emphasis_ gives italics, **strong** gives bold.
• Lines starting with - or * form a bulleted list; 1. starts a numbered one.
• [link text](https://example.com) makes a link, and the same with an exclamation mark in front embeds an image.
• Backticks mark `code`, and a line starting with > is a quotation.
• A blank line starts a new paragraph.

One name, several flavours

Gruber's original description left many details open, such as how lists nest or what happens to a stray asterisk, and different programs filled the gaps differently. In 2014 a group of developers published CommonMark, a precise specification with a test suite, which most modern tools now follow. GitHub Flavored Markdown builds on CommonMark and adds tables, task lists and strikethrough, and many other programs add extensions of their own. The media type text/markdown was registered in 2016 (RFC 7763).

The core syntax above works everywhere; tables, footnotes and other extras depend on the program that displays the file.

Where you meet Markdown

• README files and documentation in software projects, rendered by GitHub and GitLab.
• Note-taking apps such as Obsidian, which store each note as a Markdown file you own.
• Static website generators, which turn folders of Markdown into web pages.
• Chat and forum software, much of which accepts Markdown-style formatting.

Because a Markdown file is plain text underneath, everything said about TXT files, encodings included, applies to it as well. UTF-8 is the encoding to use.

How the spell checker helps

The Spell Checker opens Markdown files, checks the text for spelling, grammar and punctuation (and style, with Picky mode), and lets you download the corrected text as Markdown again, or as HTML, DOCX, PDF and the other formats it offers. The formatting symbols are ordinary characters, so they are part of the text you check. Code, file names and web addresses can show up as unknown words: leave those alone, or add a term you use often to your personal dictionary, kept in your browser, so it is not flagged again. A single check covers a whole document of up to 150,000 characters.