Supplementary content (related links, calculators, author bios, contact and policy pages) earns readers' trust. Google's helpful content questions look for "clear sourcing, evidence of the expertise involved, background about the author or the site", such as "an author page or a site's About page", but no document makes an About, Terms or Privacy page a factor in itself: unconfirmed. Claims that embedded YouTube 9 videos or other multimedia boost rankings are unconfirmed too. Add these features because visitors use them.