Google Chrome’s Ad Filtering Goes Live Tomorrow, Here’s How it Works

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As web advertisements become more intrusive, some browsers are combatting them with native ad-blocking features. Google announced plans to bring ad blocking to Chrome in June of last year, but until now, it hasn’t been clear just what it’ll look like or how it’ll work. Luckily, Google explained a bit about Chrome’s ad blocker ahead of the feature’s launch on February 15.

First of all, Chrome won’t block every ad on the web. Instead, it’ll use the Better Ads Standards, a compilation of public consumer research by the Coalition for Better Ads, as a best practices template. The policy classifies various kinds of “intrusive” ads (such as flashing animated ads) and lays out which web pages violate standards for things like high ad density and prestitial ads with countdown.

Last year, Google was able to identify 12 ad experiences that are particularly annoying to users. With that information in hand, the company created an algorithm that checks for policy violations on a sampling of web pages so that it knows which ads to block on which websites.

Here’s how it works on a technical level: when a user visits a website in Chrome, the ad filter (if enabled) first checks to see if the website complies with Better Ads Standards. If it doesn’t, Chrome then looks for things like the website’s JavaScript and images to see if they match a list of known ad-related URL patterns based on public EasyList filter rules. If there’s a match, the ads are blocked.

When ads are blocked, desktop users get a notification in Chrome’s address bar that looks similar to Chrome’s existing pop-up blocker alert. Chrome for Android users, meanwhile, get a message in a small info bar at the bottom of the screen. Folks on both platforms get an option to “always allow ads” on a site, if they so choose.

Websites found to be in violation of the Better Ads Standards can get a detailed report via the Ad Experience Report API, and request that their site be re-reviewed after they’ve addressed the non-compliant ad experiences. According to Google, 43 percent of sites which were failing the Better Ads Standards have resolved their issues and are now passing.