Ad Blockers Compared: What They Actually Block (and What They Don't)
I installed an ad blocker because I was tired of closing the same cookie popups, autoplay videos, banners, and newsletter boxes every time I opened a news site.
That was the plan, anyway.
After installing one, I opened a site I visit regularly and noticed something I hadn't expected: some ads disappeared, some page elements stayed exactly where they were, and a few things I assumed were ads weren't ads at all.
That sent me down a small rabbit hole.
I wanted to know what an ad blocker actually blocks, what it can't block, and why two different blockers can produce different results on the same page.
Ad blocking is mostly a filter-list problem
Modern browser ad blockers generally work with filtering rules. Those rules identify requests or page elements associated with advertising, tracking, annoyances, or other unwanted content and prevent them from loading or hide them from view.
AdGuard's browser extension, for example, separates its filters into categories covering advertising, privacy, social widgets, annoyances, security, and other content. It also supports custom rules and allowlists.
AdBlock uses filter lists too. Its current documentation identifies EasyList as its primary ad-blocking filter list and says that disabling it prevents AdBlock from blocking ads.
That explains something I initially misunderstood.
An ad blocker isn't a giant database containing every advertisement on the internet.
It's using rules to recognize patterns.
What ad blockers can usually remove
The obvious stuff is where they tend to work best.
Depending on the blocker, browser, filter lists, and website, that can include banner advertisements, popups, floating ads, video advertising, tracking requests, and various annoying page elements.
AdGuard currently lists video, full-screen, floating, popup, banner, and text advertisements among the types its browser extension can block. It also provides element blocking, which lets users hide unwanted pieces of a webpage.
AdBlock similarly advertises blocking for popups, banners, and video ads across supported desktop browsers. Its current Chrome Web Store listing shows more than 63 million users.
But "can block" isn't the same as "will block every time."
Why some ads still get through
This was the part that surprised me most.
Websites change.
An advertising script that was easy to identify last month can be changed, moved, or delivered differently. Filters have to keep up.
AdBlock's own support documentation has a troubleshooting section specifically for ads that aren't being blocked and recommends checking its filter lists, including EasyList and anti-circumvention filters.
AdGuard is dealing with the same general problem. Its recent updates mention improvements to filtering rules and compatibility with changing browser technologies.
So when an ad appears, it doesn't automatically mean the blocker is broken.
The filter simply may not recognize that particular ad yet.
Sponsored content is a different problem
This is where I think people sometimes expect too much from ad blockers.
If a website publishes an article titled "The Best Running Shoes for 2026" and the article itself is sponsored, an ad blocker can't necessarily turn that article into independent editorial content.
The same applies to product recommendations, affiliate links, sponsored sections, and advertising that is built directly into the site's content.
If the promotional material is part of the page's actual content rather than a separately identifiable advertising request, blocking it becomes much harder.
An ad blocker can remove an advertisement. It can't automatically determine whether every recommendation is biased.
Ad blockers don't make you anonymous
This is another mistake I made early on.
I installed an ad blocker and initially thought that meant websites couldn't track me anymore.
That's not how it works.
Some blockers include privacy protections in addition to advertising filters. AdGuard's browser extension, for example, has tracking-protection features designed to block various tracking mechanisms.
But browser-based filtering has limits.
AdGuard itself explains that browser extensions are restricted by the browser they run in and can't provide every tracking-protection feature available in its full device-level applications.
An ad blocker is therefore one privacy layer, not a guarantee that everything you do online is private.
Browser extensions don't cover every app
This became obvious when I switched from browsing on my computer to using my phone.
The extension I was using on desktop didn't magically follow me into every app.
That's because a browser extension normally operates inside its supported browser environment. AdGuard explicitly distinguishes its browser extension from its full applications, which can filter traffic across browsers and, depending on the platform, other apps as well.
AdBlock makes a similar distinction. Its current support documentation says Chrome on mobile doesn't support extensions, while its mobile products use different approaches depending on the device and browser.
So installing an ad blocker on your desktop browser doesn't mean your phone is suddenly ad-free.
There is another trade-off: websites can break
I ran into this myself.
One site I use regularly stopped displaying part of its page correctly after I enabled more aggressive filtering.
Nothing dramatic happened. The page just looked wrong.
I disabled filtering for that site, refreshed it, and the missing element came back.
This is why allowlists exist.
AdGuard lets users exclude individual websites from filtering, while AdBlock also provides allowlisting for sites where you want advertisements to remain enabled.
Sometimes the sensible choice is not "block everything."
Sometimes it's "block most things, but let this particular site work normally."
So which ad blocker should you use?
I'm not convinced there is one universal winner.
AdBlock is a large, established option with current Chrome, Firefox, and Edge support and a large user base.
AdGuard offers advertising filters alongside tracking protection, annoyance filters, custom rules, and other controls. Its current browser extension is actively maintained, with version 5.5 listed in September 2026.
What matters more than picking the name with the longest feature list is understanding what you want to block and which browser you're using.
What I expect from an ad blocker now
I no longer expect an ad blocker to make the entire internet clean.
I expect it to remove a lot of the repetitive advertising and tracking clutter that I don't want to deal with.
I also expect occasional failures.
Some ads will get through. Some websites will ask me to disable blocking. Some pages may break until I allowlist them. And an ad blocker won't tell me whether an influencer's recommendation is actually independent or whether a sponsored article is worth trusting.
That's fine.
Once I understood those limits, I stopped looking for a perfect blocker and started treating ad blocking as one browser tool among several.
That has been a much more realistic way to use it.
More practical browser, privacy, and tech tips like this are up on Tech & Rewards.