What is an .md file?

An .md file is a text file that uses Markdown, a set of plain characters that stand for formatting: # for a heading, **bold**, *italic*, a dash for a list item. To open it, use a text editor to see the raw text, or a Markdown viewer to read it formatted. The quickest way is the viewer below: drop the file in and it renders.

Markdown is a way of writing formatted documents with nothing but ordinary characters. It was created in 2004 so that a text file could be read comfortably as it is and still turn into clean formatting when a program renders it. The file extension is .md, sometimes .markdown.

The symbols you will meet most often:

• # Title, ## Section: headings, one # per level
• **bold** and *italic*: emphasis
• - item or 1. item: bulleted and numbered lists
• [text](https://example.com): a link
• > quote: a block quote
• `code` and blocks fenced with three backticks: code
• Rows with | between cells: a table

You get .md files because developers write documentation in Markdown (every GitHub project has a README.md), note apps such as Obsidian store notes as .md files, and AI assistants like ChatGPT and Claude write their answers in Markdown, so a downloaded chat or report is often an .md file.

On Windows

Double-click the file. If Windows asks which app to use, pick Notepad; you will see the Markdown as plain text with its symbols. To always open .md files the same way, right-click the file, choose Open with → Choose another app, pick the app and select Always. To read it formatted, drop it into the viewer above in Edge or Chrome.

On Mac

Right-click (Control-click) the file and choose Open With → TextEdit. TextEdit shows the plain text. Pressing the space bar in Finder gives a Quick Look preview of the same text. For the formatted version, open this page in Safari or Chrome and drop the file into the viewer.

On iPhone and iPad

Tapping an .md file in the Files app or in Mail shows its raw text. To read it formatted, open this page in Safari, tap Drop your .md file here, or click to choose, and pick the file from Files. If the file is in an email, save it to Files first.

On Android

Your Files app or Google Drive opens an .md file as text, or asks which app to use. To read it formatted, open this page in Chrome, tap the drop box in the viewer, and pick the file from Downloads.

In VS Code

Visual Studio Code reads Markdown without any extension. Open the file, then press Ctrl+Shift+V (Cmd+Shift+V on Mac) to open the formatted preview in a tab, or Ctrl+K then V to keep the source and the preview side by side while you edit.

In a browser

Dragging an .md file onto a browser window shows plain text, because browsers do not render Markdown on their own. Use a Markdown viewer instead: the one on this page, or the full Markdown viewer, which can also print the document or save it as HTML. On GitHub, .md files in a repository are shown formatted automatically.

If you forward an .md file, the next person has to repeat all of this, and on a phone they will most likely see the raw symbols. Publish it as a link instead: drop the file into the viewer above, press Publish it as a tracked link, and send the URL. It opens as a formatted page in any browser, is noindex by default, and counts its views, so you know it was read. Publishing is free for 2 public pages; Solo and Team add a password and full view tracking. See pricing, or the guide to sharing an HTML file for the same idea with HTML.