• Always include a language tag on the opening fence. It enables syntax highlighting in supporting renderers and communicates intent clearly to the reader.
• Use backtick fences (```) as the standard form; tilde fences (~~~) are less commonly expected.
• To display a code block that itself contains triple backticks, use a fence of four or more backticks or use ~~~:

~‍~‍~
```text
# This block contains triple backticks
```
~‍~‍~

Tilde Fences

A fence of three or more ~ characters works identically to backtick fences and can be used interchangeably. Tilde fences are useful when the code block itself contains backticks (also see the example on Best Practice above):

~~~markdown
Use `backticks` for inline code.
~~~

Info String

The text following the opening fence markers is called the 'info string'. Most renderers use the first word as the language identifier for syntax highlighting:

```javascript
console.log("Hello");
```

Some processors use additional words in the info string for extended features (line numbers, file names), but this is not standardised.

Fences Inside List Items

When a fenced code block appears inside a list item, it must be indented to align with the list item content and preceded by a blank line:

1. Step one.
   copy the text below and paste it into the typeface viewer

   ~~~text
   The quick brown fox jumped over the lazy dog
   ~~~

2. Step two.
   Try out different typefaces

History

Fenced code blocks were not in the original Markdown specification. They were introduced by extensions — notably PHP Markdown Extra — and later standardised by CommonMark. The indented code block (four-space indent) is the original syntax.