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.md

Markdown

Documents

MD is Markdown source text. Read either its plain-text notation or a rendered preview. Tables and task lists depend on the Markdown implementation.

What it is used for
README files, documentation and lightweight writing
What the file contains
Text
All sections, questions and sources

Content reviewed： · Editor：Kai

First: choose for your purpose

MD is Markdown text. Read source in an editor and use Markdown preview for rendered headings/links. GitHub, blogs and editors differ in supported syntax; check the destination dialect.

Opening steps

Choose your environment or purpose to see its steps.

Windows: edit and preview in VS Code

Compare source with rendered output to spot syntax mistakes.

  1. Select the MD through VS Code’s File → Open File.
  2. Run Markdown: Open Preview to the Side from the Command Palette.
  3. Inspect headings, images and links and preserve the relative folder structure.
macOS / Linux: inspect in an editor

A text editor can read the source without a Markdown app.

  1. Open the MD using a text editor such as VS Code.
  2. Inspect punctuation and indentation rather than pasting into a rich-text word processor.
  3. Check paths relative to the MD when images are missing and note network requests for external images.
Mobile / web: inspect the destination renderer

Plain-text display and Markdown rendering are different.

  1. Save the MD and open in a supporting viewer or text view.
  2. Check that image folders arrived; an MD alone omits locally referenced assets.
  3. Verify tables, code blocks and breaks in the target renderer without indiscriminately weakening preview security.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

  • Missing images may come from broken relative paths after moving only the MD file.
  • Check the renderer’s syntax rules; GitHub-specific notation may differ elsewhere.
  • Check encoding and try an appropriate encoding on a copy.
  • Code appears as prose: check opening/closing fences and indentation against the target syntax.
  • Links point elsewhere: check the relative base path and case; a local path may fail on the server.
  • Line breaks vanish: a single newline’s rendering depends on the dialect; use its documented paragraph/break syntax.

Markdown → HTML / PDF

  1. Render using the destination’s Markdown implementation; inspect links and image references.
  2. Use a compatible renderer’s PDF/print workflow and review pagination and code wrapping.
  3. Check code, tables, images and links in HTML/PDF and retain required accompanying files.

Some renderers fetch remote images. Keep referenced assets; PDF export depends on the chosen application.

Differences between renderers

Tables, task lists and math may be extensions even in CommonMark-based systems. Local rendering alone does not establish destination support.

Before reuse, check hierarchy, code, links, images and tables in the target preview and avoid exposing confidential content.

Source for these steps：CommonMark · Markdown Reference / Microsoft · Markdown and Visual Studio Code

Images and HTML export

Share MD with its image-folder structure. HTML conversion may still depend on external image files.

Source is generally text, but HTML, remote images and links depend on renderer policy. Use updated apps and avoid unnecessary execution features.

Source for these steps：Microsoft · Markdown and Visual Studio Code

Related-format differences

Related-format differences
Format / choicePurpose and preserved information
MDMarkup source whose appearance depends on the renderer.
TXTReads syntax as characters without rendering.
HTML / PDFRendered delivery copies; retain MD and source assets.

Handling and security

Review links, embedded HTML and remote images. Reading a document does not require disabling preview security.

Questions and answers

Is MD a program?

It is normally document text, but may include code examples or HTML; do not blindly run commands.

Can Notepad read README.md?

Yes; notation remains visible. Use a Markdown preview for rendered formatting.

Why does the published page differ from preview?

Renderer rules, CSS and extensions can differ. Test at the actual destination.

Does an MD alone include its images?

Locally referenced images are separate files; share their folder structure too.

Does HTML conversion guarantee identical display?

CSS, fonts and external assets still affect appearance; verify at the destination.

Format facts: name, steward and MIME type
Formal name
Markdown source text
Steward / specification
Markdown implementations / CommonMark
MIME type
text/markdown

Primary and official sources

  • Project documentationMarkdown Reference

    Reference for headings, links and other basic Markdown notation.

    CommonMark · Link checked：
  • Software documentationMarkdown and Visual Studio Code

    Documents editing, previewing and preview security.

    Microsoft · Link checked：