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MD
What is an MD file?
Plain text with light formatting marks. What most documentation and README files are written in.
What MD is
MD is a plain-text format you can open in any editor. It is used for editing and moving data between programs.
The extension is .md, and the full name is Markdown. Both matter less than what the file can hold, which is what the rest of this page is about.
Where MD came from
It dates from 2004. The specification is CommonMark.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
What opens MD
Visual Studio Code, Obsidian and Typora read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
No browser reads it.
That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.
It is a working format
MD is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.
The facts, in one place
| Extension | .md, .markdown |
|---|---|
| Media type | text/markdown |
| First published | 2004 |
| Specification | CommonMark |