# Syntax

Syntax extensions add author-facing Markdown constructs to a trusted factory
profile. Enable only the constructs accepted by the document format.

## Extensions

- [Paired delimiters](https://altophp.com/markdown/syntax/paired-delimiters.md): define safe inline delimiter pairs.
- [Smart punctuation](https://altophp.com/markdown/syntax/smart-punctuation.md): replace quotes, dashes, and ellipses.
- [Highlight](https://altophp.com/markdown/syntax/highlight.md): mark inline text with paired delimiters.
- [Description lists](https://altophp.com/markdown/syntax/description-lists.md): render terms and definitions.
- [Footnotes](https://altophp.com/markdown/syntax/footnotes.md): connect references to endnotes.
- [Tabs](https://altophp.com/markdown/syntax/tabs.md): group nested content into accessible panels.
- [Mentions](https://altophp.com/markdown/syntax/mentions.md): resolve application-specific references.
- [Attributes](https://altophp.com/markdown/syntax/attributes.md): attach constrained attributes to elements.

Each guide shows installation, configuration, Markdown input, HTML output,
options, and its security boundary.