What is an .md file?

Ask an AI assistant to write something up for you, and you often get back a file with an unfamiliar extension: .md. Open it and the text is littered with # and **, which makes it hard to read. Is this some kind of code? Something you shouldn’t touch? It throws most people the first time. This post explains what .md files are, and how to open one so it actually reads like a document.

An .md file is a text file with formatting marks

.md files are written in Markdown. The contents are plain text, so Notepad on Windows or TextEdit on Mac will open them without any trouble. As you have seen, though, all those symbols get in the way.

Here is the thing: each symbol means something.

• # Heading — a top-level heading
• ## Heading — a subheading
• **bold** — bold text
• - item — a bullet point

So when you see **important**, that is an instruction to whatever software displays the file: “show the word important in bold.” In Word or a rich-text notes app, you would select the text and click a button to do the same thing. Markdown just writes that instruction inline as a symbol instead. It is a notation — a set of writing conventions — and nothing more. The file itself is no different from a plain .txt.

So why do the symbols still show up?

If the whole point of Markdown is to mark up headings and bold text, why doesn’t Notepad just display it that way? It is a fair question, and the answer is simpler than you might expect.

Notepad and TextEdit display the symbols as they are, rather than acting on them. These are plain text editors, built to handle a text file without altering it. To have those instructions interpreted and reflected on screen, you need software that understands Markdown.

Open the same file in a tool that does, and # Heading becomes a large heading, **bold** becomes bold text, and the symbols vanish from view. Results vary between tools, but the text is laid out to be read comfortably. A Markdown viewer does for your file roughly what typesetting does for a manuscript: the same words, arranged so a person can actually read them.

Ways to open one

There are several options, and they suit different situations. It is worth finding the one that fits how you work.

1. Open it in a browser — use a web tool like yomeru. The quickest route
   Pros: nothing to install, works right away
   Cons: so many options that choosing is a chore, and quality varies

2. Use a code editor — VS Code and similar tools have a preview pane. Suited to people who already write code
   Pros: edit and preview side by side, opens locally in an instant
   Cons: requires installation, and the interface takes some learning

3. Convert it to Word — run it through an md-to-docx converter
   Pros: opens in a tool you already know
   Cons: an extra step every time

4. Add a browser extension — install an extension that renders Markdown
   Pros: view files from anywhere in your browser
   Cons: requires installation, and only works in certain browsers

How a tool sets the type is part of its character. Whether the result is pleasant to read is a perfectly good reason to pick one over another.

If you are not sure where to start, option 1 needs no installation, so try that first.

Wrapping up

So — an .md file is not a cryptic code, and it is certainly not a program you need to be careful around. It is an ordinary text file with a few instructions added to make it look better. If you need to change something, go ahead and edit it; there is nothing to break (yomeru even lets you edit the file and save your changes straight back to it). The only real catch is that tools for reading these files are still thin on the ground.

Markdown is lightweight and easy to work with, and once it clicks, anyone can produce a readable document quickly. It is also becoming the standard text format for working alongside AI.

Go find the .md viewer that suits you.