These are scripts that are loaded on a website that try to detect if the user is employing an ad-blocking extension and allows sites to show a notification through which they ask the user to allow ads on the site by disabling the ad blocker or by whitelisting the site.
Researchers looked for two of the most popular anti-adblock solutions, namely Anti-Adblock Killer List and the Combined EasyList (Adblock Warning Removal List + Anti-Adblock sections in EasyList). The percentage comes from a research project carried out by academics from the University of Iowa and University of California-Riverside that reviewed the use of anti-adblock scripts in the past five years.
Around 9% of today's most popular websites deployed or are deploying anti-adblock scripts in an effort to maintain advertising revenues and fight off the rise in the adoption of ad-blocking extensions.
