The <em>Content</em> and <em>Help</em> search types provided by the core software pre-index their content and store the results in several database tables that are collectively called the <em>search index</em>. The process of indexing renders the content and breaks it up into words, which can then be matched more efficiently with keyword queries when users perform searches. Search indexing happens during cron runs; see @cron_topic for more information about cron.