Basic Markdown syntax.

01Fast acquisition

Basic syntax quick reference.

Use this table when you know the element and only need the pattern. The detailed sections below cover parsing behavior and failure points.

02Document hierarchy

Headings.

Put one to six number signs at the start of a line. The count becomes the heading level: one marker produces an h1, two produce an h2, and the sequence continues through h6.

# Mission overview
## Flight plan
### Preflight checks

<h1>Mission overview</h1>
<h2>Flight plan</h2>
<h3>Preflight checks</h3>

Setext headings

Markdown also supports an underline form for the first two levels. A line of equals signs creates level one. A line of hyphens creates level two. This syntax is valid, but marker-based headings are easier to scan and extend beyond two levels.

Mission overview
================

Flight plan
-----------

<h1>Mission overview</h1>
<h2>Flight plan</h2>

03Text flow

Paragraphs and line breaks.

A blank line separates paragraphs. Pressing Enter once usually keeps text in the same paragraph, even though the source moves to a new line. This lets teams wrap source text without changing the rendered document.

The payload passed inspection.
The source can wrap here.

Launch remains scheduled for 09:30 UTC.

<p>The payload passed inspection. The source can wrap here.</p>
<p>Launch remains scheduled for 09:30 UTC.</p>

Hard line breaks

To force a break inside one paragraph, end the first line with two spaces before pressing Enter. Those spaces are invisible, which makes them easy to remove by accident. CommonMark also recognizes a backslash at the end of a line. The HTML <br> tag is another option where raw HTML is allowed.

Launch site: Cape Canaveral  
Window: 09:30 UTC

<p>Launch site: Cape Canaveral<br>
Window: 09:30 UTC</p>

04Signal strength

Bold, italic, and combined emphasis.

Wrap text in one asterisk for italic, two for bold, or three for both. Underscores can produce the same elements, but asterisks are more predictable when emphasis appears inside a word.

Telemetry is *still arriving*.

The launch state is **GO**.

This warning is ***mission critical***.

<p>Telemetry is <em>still arriving</em>.</p>
<p>The launch state is <strong>GO</strong>.</p>
<p>This warning is <em><strong>mission critical</strong></em>.</p>

05Quoted transmission

Blockquotes.

Start a quoted paragraph with a greater-than sign. For a multi-paragraph quote, include the marker on the blank line between paragraphs. Add another marker to nest a quote.

> The first signal arrived at 09:07 UTC.
>
> **Control:** Maintain the current trajectory.
>
>> Guidance confirms the correction.

<blockquote>
<p>The first signal arrived at 09:07 UTC.</p>
<p><strong>Control:</strong> Maintain the current trajectory.</p>
<blockquote><p>Guidance confirms the correction.</p></blockquote>
</blockquote>

06Sequence control

Ordered, unordered, and nested lists.

Ordered items begin with a number and period. Unordered items begin with a hyphen, asterisk, or plus sign. Use one marker style throughout a list. Consistency makes the source easier to review and avoids processor differences.

1. Inspect the payload.
2. Verify the checksum.
3. Open the launch channel.

<ol>
<li>Inspect the payload.</li>
<li>Verify the checksum.</li>
<li>Open the launch channel.</li>
</ol>

- Flight systems
  - Guidance
  - Telemetry
- Ground systems
  1. Network check
  2. Recorder check

<ul>
<li>Flight systems<ul><li>Guidance</li><li>Telemetry</li></ul></li>
<li>Ground systems<ol><li>Network check</li><li>Recorder check</li></ol></li>
</ul>

Paragraphs and code inside a list

A list item can contain more than one paragraph, a blockquote, an image, or a code block. Indent the added block so the processor knows it belongs to that item. Fenced code is much easier to maintain inside a list than an indented code block.

07Literal channel

Inline code and code blocks.

Wrap a command, filename, variable, or short literal in one backtick. The processor will treat the contents as code instead of parsing Markdown markers inside it.

Run `npm run build`, then inspect `dist/index.html`.

<p>Run <code>npm run build</code>, then inspect <code>dist/index.html</code>.</p>

Indented code blocks

Indent every code line by four spaces or one tab. This is part of basic Markdown, but it becomes difficult to maintain inside nested lists.

    const status = "go";
    console.log(status);

<pre><code>const status = &quot;go&quot;;
console.log(status);
</code></pre>

const status = "go";
console.log(status);

Fenced code blocks

CommonMark, GitHub Flavored Markdown, and most modern tools support code fences made from three backticks or tildes. An optional language name can enable syntax highlighting. Fences are easier to copy, nest, and review than four-space indentation.

```javascript
const status = "go";
console.log(status);
```

<pre><code class="language-javascript">const status = &quot;go&quot;;
console.log(status);
</code></pre>

const status = "go";
console.log(status);

08Section separation

Horizontal rules.

Put three or more hyphens, asterisks, or underscores on a line by themselves. Blank lines above and below protect the rule from being interpreted as a Setext heading underline.

Telemetry complete.

---

Begin post-flight review.

<p>Telemetry complete.</p>
<hr>
<p>Begin post-flight review.</p>

09Navigation channel

Inline, automatic, and reference links.

An inline link puts the visible label in square brackets and the destination immediately after it in parentheses. Add a quoted title after the URL only when the extra tooltip is useful.

Read the [mission brief](/brief "Current mission brief").

<p>Read the <a href="/brief" title="Current mission brief">mission brief</a>.</p>

Automatic links

Angle brackets can turn a complete URL or email address into a link: <https://www.sputnikfx.com/>. Some processors detect bare URLs without brackets, but that behavior is an extension.

Reference-style links

Reference links move long destinations away from the sentence. The first part stays in the paragraph. A labeled definition can sit after that paragraph or at the end of the document.

The [launch archive][archive] remains public.

[archive]: https://example.com/archive "Launch archive"

<p>The <a href="https://example.com/archive" title="Launch archive">launch archive</a> remains public.</p>

10Visual payload

Images and linked images.

Image syntax starts with an exclamation mark, followed by alternative text in square brackets and the asset path in parentheses. An optional quoted title may follow the path.

Image with alternative text

Markdown source

![Sputnik Digital Graphics icon](/logos/favicon/favicon.svg "Sputnik Digital Graphics")

Generated HTML

<img src="/logos/favicon/favicon.svg" alt="Sputnik Digital Graphics icon" title="Sputnik Digital Graphics">

Rendered result

Alternative text should describe the image purpose. Do not repeat a nearby caption word for word.

Linked images

Wrap the complete image syntax in link brackets, then add the destination:

[![Sputnik icon](/logos/favicon/favicon.svg)](https://www.sputnikfx.com/)

Basic Markdown has no portable image-sizing syntax. Use a properly sized source asset, a processor extension, or an HTML img element when the platform safely allows HTML.

11Literal characters

Escaping Markdown characters.

Add a backslash before punctuation when you need the literal character instead of its formatting behavior. This is useful for asterisks, list-like numbers, brackets, and other symbols that might start Markdown syntax.

\*This text keeps its asterisks.\*

1969\. Apollo 11 landed on the Moon.

<p>*This text keeps its asterisks.*</p>
<p>1969. Apollo 11 landed on the Moon.</p>

12Direct markup

HTML inside Markdown.

Many Markdown processors pass HTML tags through to the rendered document. HTML can handle details that basic Markdown does not express, such as image dimensions or specialized semantic elements. Support is a platform decision, not a guarantee.

This status is <mark>under review</mark>.

<p>This status is <mark>under review</mark>.</p>

Put blank lines around block-level HTML such as div, table, or details. Markdown inside an HTML block may stop parsing unless the processor explicitly supports it.

13Cross-platform flight

Compatibility checklist.

The fastest way to make Markdown portable is to remove ambiguity from the source. These rules survive more processors, editors, static-site generators, and documentation platforms.

• Use blank lines around headings, lists, blockquotes, code blocks, and horizontal rules.Blocks should be visually separate in the source.
• Put a space after heading markers.Write ## Flight plan, not ##Flight plan.
• Use asterisks for emphasis inside words.Underscore behavior differs across processors.
• Start ordered lists with 1. and use periods.Parenthesis delimiters are less portable.
• Keep unordered-list markers consistent.Do not switch between hyphens, plus signs, and asterisks in one list.
• Encode spaces and difficult punctuation in URLs.Raw spaces can terminate or break a destination.
• Use HTML only when the destination permits it.Some platforms sanitize tags or disable raw HTML completely.
• Preview in the processor that will publish the document.A README on GitHub and a local PDF export may not use identical extensions or styles.