Facebook Security Update, Protection from Untrustworthy Websites With Web Of Trust (WOT) The add-on works with Firefox, Google Chrome, Internet Explorer, Opera and Safari and is a free download from www.mywot.com. When a Facebook user clicks a link that leads to a page with a poor reputation rating given by the WOT community, Facebook shows a warning message. WOTs global community has reported five million sites for phishing, untrustworthy content, fraudulent services or various scams.
Source: https://thehackernews.com/2011/05/facebook-security-update-protection.html