How do I temporarily highlight a custom text pattern in my buffer without changing the syntax file?

Explanation

:match lets you apply a highlight group to any pattern in the current window without touching the buffer or its syntax rules. It's a quick way to draw attention to a specific pattern — TODOs, a variable name, overly long lines — during a session.

How it works

• :match {group} /{pattern}/ applies the named highlight group to all matches of {pattern} in the active window
• :match (no arguments) or :match none clears the match
• Vim provides two additional layers: 2match and 3match, giving you up to three independent concurrent highlights
• Groups like Error, Todo, Search, WarningMsg, or any custom highlight group can be used

Example

Highlight all occurrences of TODO in red using the built-in Todo group:

:match Todo /TODO/

Highlight lines longer than 80 characters:

:match ErrorMsg /\%>80v./

Use a second layer for a different pattern simultaneously:

:2match WarningMsg /FIXME/

Clear all custom matches:

:match none
:2match none

Tips

• Matches are window-local, so different windows can show different highlights
• :highlight lists all available groups you can pass to :match
• For persistent per-filetype highlights, prefer syntax match in a syntax file; use :match for quick ad-hoc sessions