You've seen the file. It ends in .md. You opened it and got a wall of text full of # symbols, asterisks, and square brackets. It looks messy. It's actually very simple — and once you understand it, you'll recognise markdown everywhere.

This guide is for non-developers who want to understand what markdown is, why it's showing up on their computer, and how to read these files properly.

Markdown in Plain English

Markdown is a way of adding formatting to plain text using simple symbols. Instead of clicking "Bold" in a menu like you would in Microsoft Word, you put **asterisks** around the text you want to make bold. Instead of choosing a heading size from a dropdown, you put # at the start of a line.

The idea is that the symbols are simple enough to be readable even before they're formatted — and when you open the file in a markdown-aware viewer, all those symbols disappear and you see a properly formatted document.

Here's what the main symbols look like:

Symbol	What it does	Example
`# Heading`	Big heading	`# My Document` → My Document (large)
`## Subheading`	Smaller heading	`## Section 1`
`bold`	Bold text	`important` → important
`italic`	Italic text	`note` → note
`- item`	Bullet list	`- First point`
`1. item`	Numbered list	`1. First step`
`code`	Inline code	`function()`
`[text](url)`	Link	`[Click here](https://example.com)`

That's most of what you'll see in a typical markdown file. A few more symbols for tables and code blocks, but the fundamentals are quick to learn.

Why Markdown Files Are Everywhere Now

Until recently, markdown was mostly used by software developers — writing documentation, project descriptions on GitHub, and technical notes. If you weren't technical, you could go years without seeing a .md file.

That's changed, for a few reasons.

AI tools output markdown constantly. If you've used Claude, ChatGPT, Copilot, or any AI writing assistant, you've received markdown. When Claude writes a plan with bullet points and headings, it's writing markdown. When ChatGPT generates structured output, it's markdown. When you export an AI conversation, you get a .md file. AI tools have made markdown ubiquitous for everyone who uses them — not just developers.

GitHub and software projects. Every software project on the internet uses a README.md as its project description. If someone has sent you a software project or included it in a download, there's a README.md in there.

Documentation and note-taking tools. Notion, Obsidian, Linear, and many other tools use or export markdown. If you work with teams that use these tools, you'll see .md files.

It's becoming a standard. Just as PDF became the standard for sharing documents that look the same everywhere, markdown is becoming the standard for text that should be portable and readable anywhere.

What You'll Typically Find in a .md File

Depending on where it came from:

From an AI tool — Probably a document with sections and structure. A plan, a summary, a technical explanation, a piece of writing. Often with headings, bullet points, and maybe tables.

From a software project — A README explaining what the project does, how to install it, and how to use it. Will have headings, code blocks (the grey boxes with code in them), and probably some lists.

From a note-taking app — Someone's notes, exported as plain text with markdown formatting. Could be anything.

From documentation — A manual or guide, with headings for sections, numbered steps, and links.

The Problem: Opening .md Files Without the Right Tool

When you double-click a .md file on a Mac, it often opens in TextEdit. TextEdit shows you the raw text — all those # and ** symbols — because it doesn't know about markdown formatting.

It's like opening a Word document in a text editor and seeing all the XML and formatting codes underneath. Technically the content is there, but it's not readable.

You need a markdown-aware viewer to see it properly.

How to Open .md Files Properly on Mac

The quick option: open it in a web browser. Drag a .md file onto Safari or Chrome. The browser may or may not render markdown depending on extensions — often it shows the raw text. Not ideal.

The developer option: VS Code. If you have Visual Studio Code installed, you can open .md files and use its markdown preview. Works well but VS Code is a big application designed for writing code, not reading documents.

The best option: a dedicated markdown reader. An app built specifically for markdown opens the file and shows you the formatted version immediately. No split panes, no extensions needed.

OpenMark is a native Mac app (built for macOS Tahoe) that does exactly this. Open a .md file and you immediately see:

Proper headings in different sizes
Formatted bullet points and numbered lists
Bold and italic text
Highlighted code blocks
Tables with proper columns
If there are any diagrams (Mermaid) or math formulas (LaTeX), those render too

You can also click into any part of the document to edit it, if needed.

To set OpenMark as the default so .md files open in it automatically: right-click any .md file in Finder → Get Info → Open With → select OpenMark → Change All…

Do You Need to Learn Markdown?

Not really. If you're just opening and reading markdown files, you don't need to learn the syntax — you just need the right viewer. With OpenMark, you see the formatted output, not the symbols.

But if you find yourself wanting to edit markdown files, or write your own notes in markdown, the learning curve is genuinely small. The basics take about 15 minutes to pick up, and after that you'll be able to write formatted text without ever taking your hands off the keyboard.

For a more detailed look at what markdown can do, Markdown for Developers: README Files, Documentation, and More covers the full feature set — tables, task lists, code blocks, diagrams.

For a guide on setting up OpenMark as your default markdown viewer on Mac, see How to Open .md Files on Mac: The Complete Guide.

Download OpenMark → — $9.99, one-time, native macOS. Open any .md file and read it the way it was meant to look. No technical knowledge required.