What is an MD file?
An MD file stores ordinary text plus lightweight punctuation that describes the document structure. The file stays readable in a basic text editor; the formatted appearance appears only after a Markdown renderer processes that syntax.
# Project Notes
This is a **Markdown file**.
- Review changes
- Publish updatesProject Notes Heading 1
This is a Markdown file. Bold text
• Review changes
• Publish updates# Headingprocess syntaxHeading| Term | Meaning |
|---|---|
| Markdown | A lightweight markup language used to structure text |
| MD file | A plain-text file containing Markdown |
| .md extension | The filename extension commonly used for Markdown files |
| Markdown renderer | Software that turns Markdown syntax into formatted output |
What is README.md?
README.md is a Markdown file with a conventional name. Software projects commonly use it to explain what a project does, how to install or use it, and where to find more documentation. GitHub renders README.md in a repository, which is why visitors usually see a formatted project page rather than the raw punctuation.
README.md is not a separate file format. It is simply an MD file used as a project introduction.
How do you open an MD file?
Choose an app based on what you need to do. A text editor shows the Markdown source. A Markdown editor or preview shows the rendered document. Opening the source and rendering it are two different actions.
| Goal | Use | What you see |
|---|---|---|
| Read or edit the source | Any plain-text or code editor | Markdown punctuation and text |
| Check the formatting | A Markdown preview or renderer | Rendered headings, lists, links, and code |
| Continue in an office workflow | Convert to DOCX first | An editable Word document |
How to open and create an MD file on Windows
Open an existing .md file with a text editor or code editor. If the editor only shows #, *, backticks, and other symbols, it is displaying the source correctly; use a Markdown preview when you want the formatted view.
- Create a plain-text documentWrite the Markdown in a text editor.
- Choose Save AsSet Save as type to All Files and choose UTF-8 encoding when the editor offers it.
- Use the .md extensionSave the file as notes.md, not notes.md.txt. Turn on visible file extensions if Windows hides the final .txt suffix.
How to open an MD file on macOS, Linux, and VS Code
On macOS, TextEdit can open an MD file, but choose Format → Make Plain Text before creating or saving one. Rich-text mode can produce a document that only looks like text. A dedicated Markdown or code editor is more convenient when you also need a live preview.
On Linux, open the file with any plain-text or code editor. Markdown rendering depends on the application, not the operating system. VS Code includes Markdown editing and a built-in preview; open the file, then use Ctrl+Shift+V on Windows or Linux, or Cmd+Shift+V on macOS.
Can a browser open an MD file?
A browser may show raw text or a formatted page depending on the website, the server response, and the viewer handling the file. GitHub renders Markdown as part of its interface. A server may instead deliver the source as text. Opening a local .md file in a browser does not automatically make the browser a Markdown renderer.
Common MD file problems
Most MD file problems come from the filename, the viewer, or paths to related assets rather than from the text format itself.
| Problem | Likely cause | What to do |
|---|---|---|
| The file shows # and * symbols | You opened the source | Open a Markdown preview to see the formatted result |
| The file became notes.md.txt | The editor added a text extension | Use All Files and make extensions visible before renaming |
| Images disappear | A relative path no longer matches the file location | Move the image with the MD file or correct the path |
| A table does not render | The viewer may not support GFM tables | Test the document in the final publishing environment |
| Formatting changes between apps | Markdown extensions and styles differ | Check the target renderer rather than relying on one preview |
How to edit and convert an MD file
Edit MD files with any plain-text editor, VS Code, a Markdown editor, or an online editor. After making changes, preview the document and check the elements that can vary between renderers: tables, task lists, images, code fences, and line breaks.
Convert the file when the next person or system needs another format. PDF is useful for a fixed document, DOCX for office editing, and HTML for web publishing. Microsoft Word is not a Markdown renderer; convert the Markdown to DOCX when you want a native Word workflow.
MD vs TXT vs HTML
All three can contain readable text, but they serve different jobs. Markdown adds a small, human-readable set of structure markers; HTML uses tags for web documents; TXT has no shared formatting syntax.
| File type | Purpose | Example |
|---|---|---|
| .md | Structured plain text using Markdown | README.md |
| .txt | Unformatted plain text | notes.txt |
| .html | A web document using HTML tags | index.html |
Official references
These primary references document the syntax and application behavior discussed in this guide.
Markdown basics FAQs
Can I open an MD file without installing software?
Yes. Any plain-text editor can open it. Use an online or built-in Markdown renderer if you also need a formatted preview.
Can Microsoft Word open Markdown as a formatted document?
Word is not a Markdown renderer. It may open the source as text, but converting the file to DOCX creates a more useful editable Word document.
Does every Markdown app render the same way?
No. Core syntax is broadly consistent, but tables, task lists, footnotes, and other extensions can vary. Test important content in the final renderer.
Is README.md different from another MD file?
No. README.md uses the same file format; its filename simply signals that it introduces a project or folder.