What is an MD file?

An MD file is a plain-text document written in Markdown. It stores your words alongside simple marks for headings, emphasis, lists and links. A Markdown viewer turns those marks into a formatted page.

You might receive one as a report from an AI conversation, a set of meeting notes or a README explaining a software project. All can use the same format.

The file holds the words and their structure

In Markdown, a line beginning with # is a heading. Two asterisks on each side of a phrase, like **Friday**, mark it as bold. Those characters are part of the saved text.

For example, a file could contain:

# A day by the coast

Leave on **Friday**.

- Pack a picnic
- Check the weather

A viewer displays a heading, a bold “Friday” and a two-item list. A plain-text editor shows the marks themselves. Both apps are opening the same document.

Markdown was designed to be readable as plain text. Short notes often work well in either form; longer documents with links and tables are easier to follow once the formatting is applied. Our opening guide shows the source and formatted versions side by side.

Why it looks different in different apps

Some apps format Markdown; others show it as ordinary text. When an AI chat displays a Markdown heading, you see the formatted result. Open the downloaded text in a plain-text editor and the heading marks become visible again.

Even two Markdown viewers can make the document look different. A heading mark identifies the line as a heading; the app chooses its font, colour and spacing.

Markdown carries the words and structure between tools. If the precise page layout matters, such as a document designed for printing, a PDF is a better format for preserving that appearance.

Some formatting needs extra support

There are different versions of Markdown. CommonMark defines a shared set of rules; GitHub Flavored Markdown adds features such as tables. Equations and diagrams may depend on further extensions. Without support for them, an app may show the underlying notation instead of the intended result.

Images have another dependency. Markdown documents often refer to images stored elsewhere. A file that refers to an image in a nearby folder needs that image too. Copying only the MD file may leave the reference pointing nowhere.

Reading and editing an MD file

To read a formatted copy, use a Markdown viewer. Easy Markdown is a free online viewer for headings, lists, tables and links. It doesn’t render images, equations or diagrams. You can open your file here without an account or installation.

To change the original, use a text editor or Markdown editor. If you prefer working in Google Docs, import the Markdown file to create an editable document there. Keep the original MD file if you also want a copy in Markdown format.