Here is how Real Obvious Highlight works... Page Viewer - Highlighted text is displayed embedded in wiki pages to the viewer. Page Editor - Highlighted text is added to a page using standard MediaWiki Templates "{{Highlight|...}}" Wiki Admin - Real Obvious Highlight is installed by creating the Highlight template.

Nothing. Real Obvious Highlight is provided free of charge.

Compatibility, Simplicity, and Cost. Compatibility - To ensure the widest possible compatibility across MediaWiki servers, Real Obvious Highlight is installed as an enhancement (not a plugin). Installing Real Obvious Highlight is easy as 1 (no 2 or 3) -- Step 1) Create the MediaWiki Highlight Template. Simplicity - MediaWiki Templates are used to add "Highlight" [...]

Real Obvious Highlight is a MediaWiki Enhancement designed to be installed and used on MediaWiki websites connected to the Internet or operated within isolated enclaves / dark sites.