What is a .md file?
A plain-text file written in Markdown — readable as-is, and designed to become something else.
Convert Markdown to PDF
Markdown source
Text that carries its own formatting
A .md file is an ordinary text file. You can open it in Notepad or TextEdit and read every character, because there is no hidden formatting data — no invisible styling layer of the kind a Word document carries. What makes it a Markdown file is a convention: a handful of punctuation marks stand in for formatting. A line starting with # is a heading. Text wrapped in **asterisks** is bold. A line starting with - is a list item.
John Gruber designed the format in 2004 with a specific goal: the source should be readable by a human before it is processed by anything. That is why the syntax uses characters people already used in plain-text email — asterisks for emphasis, hyphens for lists. A Markdown file is legible whether or not you have software that understands it, which is precisely what makes it durable.
The extension is usually .md, occasionally .markdown, and rarely .mdown or .mkd. They are the same format; the extension is only a hint to your software. A .txt file containing Markdown is still Markdown — the computer just will not guess as much.
Because the format is plain text, it works with the tools built for plain text. Git can show you a meaningful line-by-line diff of a Markdown document, which it cannot do for a .docx. That single property is why nearly every software project writes its documentation in it.
How to turn a .md file into something else
Open or paste the file
Drop the .md file onto the converter above, or paste its contents. Markdown is text, so pasting works just as well as uploading.
Pick the format you need
PDF to send or print, Word if someone has to edit or comment, HTML for the web, plain text to paste into an email.
Download
The file is produced in your browser and saved to your device.
MD file, .md file, Markdown file — all the same thing
These are three names for one format. “MD” is just the file extension read aloud, and Markdown is the name of the syntax inside. If someone sends you an MD file and you cannot open it, nothing is wrong with the file — you simply need something that renders Markdown, or a converter that turns it into a format your software already knows.
Questions
Is a .md file the same as a text file?
Technically yes — it is plain text, and renaming it to .txt loses nothing. The difference is convention: the .md extension tells software that the punctuation inside means formatting, so an editor knows to render # as a heading rather than print a hash.
Why do developers use Markdown instead of Word?
Because it is plain text, so it works with version control. Git can show exactly which line of a document changed between two versions, which is impossible with a binary format like .docx. Markdown also renders natively on GitHub, GitLab, and most developer tools.
Can I edit a .md file without special software?
Yes. Any text editor works — Notepad on Windows, TextEdit on Mac, or anything else. Dedicated Markdown editors add a live preview, but nothing about the format requires them.
What is the difference between .md and .markdown?
Nothing. Both extensions mean the same format, and .md is simply shorter and far more common. You will also see .mdown and .mkd occasionally, which are equally interchangeable.
Why does my .md file show symbols instead of formatting?
You are looking at the source rather than a rendered view, which is normal in a plain text editor. The symbols are the formatting. To see it rendered, open it in a Markdown editor, view it on GitHub, or convert it to PDF or HTML.
Are .md files safe to open?
Yes. A Markdown file is text and cannot execute anything on its own. That is one of its advantages over document formats that support macros.