# Highlight languages (/docs/reference/languages)

> Every language and alias a code window highlights, each with a sample line colored by the renderer's own highlighter.

A `terminal` section's `lang`, and every code window a Section type draws, names one of these. The highlighter is small and fixed: keywords, strings, comments and the added and removed lines of a diff. A name it does not know is refused at its path, as [Closed sets](https://next.mdxui.dev/docs/reference/closed-sets#languages) lists.