Even after the ad is blocked, a "hole" might be left in the website's layout. Modern extensions parse the site’s source code to "unfuck" the layout, hiding the empty frames or containers where the ads would have been.
For the average user, the advantages of installing an adblock extension are immediate and tangible: adblock extension
At its core, an adblock extension is a content-filtering tool for your web browser. It doesn't just "see" an ad and hide it; rather, it uses complex mechanisms to prevent ads from loading in the first place. Even after the ad is blocked, a "hole"