Highlighter is nothing but a highlighting implemented method that actually performs the activity. There are three methods available for highlighting. They are unified, original, and fastVector. To implement highlighting, first we need to specify one method to hl.method. If we do not select any method, the default original method performs the activity.

There are many parameters supported by highlighters. Sometimes, the implementation details and semantics will be a bit different, so we can't expect identical results when switching highlighters. Normally, highlighter selection is done via the hl.method parameter, but we can also explicitly configure an implementation by class name in solrconfig.xml. Let's explore highlighters in detail.