Chrome’s built-in ad blocker will go live tomorrow. It’s the first time Google will automatically block some ads in Chrome, but while quite a few online publishers are fretting about this move, as a regular user, you may not even notice it.

The most important thing to know is that this is not an alternative to AdBlock Plus or uBlock Origin. Instead, it’s Google’s effort to ban the most annoying ads from your browser. So it won’t block all ads — just those that don’t conform to the Coalition for Better Ads guidelines. When Google decides that a site hosts ads that go against these guidelines, it’ll block all ads on a given site — not just those annoying prestitials with a countdown or autoplaying video ads with sound.

Here are the kinds of ads that will trigger the new ad blocker in Chrome:

If you end up on a site where Chrome is blocking ads, you’ll see a small pop-up in Chrome (yeah — Chrome will pop up a notification to alert you when it blocked a pop-up…) that gives you the option to sidestep the ad blocker and allow ads on that site.

Under the hood, Google is using the same patterns as the public and community-curated EasyList filter rules. It’s worth noting that while Google made some modifications to those rules, it doesn’t exempt its own ad networks  from this exercise. If a site is in violation, ads from AdSense and DoubleClick will also be blocked.

Chances are that you’ll see a bit of a performance boost on sites where ads are being blocked. That’s not the focus here, though, and Google says it’s at best a secondary effect. Some early ad blockers also had some issues with excessive memory usage that sometimes slowed down the browser. Google admits that there is some memory overhead here to hold the blocking list in memory, but even on mobile, that’s a negligible amount.

It’s worth noting that the recommendations of the Coalition for Better Ads focus on North America and Western Europe. Because of this, those are also the regions where the ad filtering will go live first. Google, however, is not classifying sites by where the individual Chrome user is coming from. Instead, it’s looking at where the majority of a site’s visitors come from. So if a user from India visits a site in Germany where ads are being blocked, that user won’t see ads even if the filtering isn’t live for Indian sites.As Google’s product manager for the Chrome Web Platform Ryan Schoen told me, 42 percent of publishers that were in violation have already moved to other ads. Of course, that means the majority of sites that Google warned about this issue did not take any action yet, but Schoen expects that many will do so once they see the impact of this. While ad blockers are often among the most popular extensions, they don’t come pre-installed, after all. This one does, and Google’s approach of blocking all ads on a site will surely sting.

Indeed, this decision to block all ads may seem rather harsh. Schoen, however, argues that it’s the only practical solution. In Google’s view, publishers have to take responsibility for the ads they show and take control of their ad inventory. “The publisher can decide which ad networks to do business with but ultimately for us, the users, by navigating to a specific site, they enter a relationship with that site,” he said. “We do think it’s the responsibility of the site owner to take ownership of that relationship.”

Still, so far, it looks like Chrome will only block just less than one percent of all ads — something that will make some publishers breathe a sigh of relief and scare others. For users, though, this can only be a good thing in the long run.

Featured Image: Getty Images