# What does an ad blocker do for a web browser? **URL:** \ **Category:** Factual Questions\ **Created:** [May 5, 2021, 5:51pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454 "2021-05-05T17:51:10Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Yelnick\_McWawa](https://avatars.discourse-cdn.com/v4/letter/y/839c29/32.png) [@Yelnick\_McWawa](https://boards.straightdope.com/u/Yelnick_McWawa)\ **Post date:** [May 5, 2021, 5:51pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/1 "2021-05-05T17:51:10Z")
What does and ad blocker do for a web browser? What does it block? Unbeknownst to me, I have an ad blocker on my PC. I occasionally get a banner asking me to disable the aforesaid ad blocker. The banner usually obscures whatever I’m trying to read. What are these advertisements that I am blocking? If they wanted me to buy a DeLorean, why not have the banner say, “Freddie’s Auto Sales Has DeLoreans in stock” instead of “Disable your ad blocker”? From a different point: If they want me to look at an advertisement, why not put that advertisement in the form of a JPEG photograph on the web page I’m browsing. Digitally, I don’t’ think software can differentiate a JPEG porn photograph from an advertisement. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [May 5, 2021, 6:00pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/2 "2021-05-05T18:00:05Z")
> [@Yelnick\_McWawa](#): > > From a different point: If they want me to look at an advertisement, why not put that advertisement in the form of a JPEG photograph on the web page I’m browsing. Digitally, I don’t’ think software can differentiate a JPEG porn photograph from an advertisement. Because they don’t just want you to look at an advertisement, they want to prove to the advertiser that you looked at the advertisement. Most websites hand off the problem of solving this to someone like Google who will be selling the ads and recording how many viewers an add has through that website. The methods used for that are what enables an ad-blocker to figure out what parts of a website are ads. Ad-blockers can also block cookies, and for many different reasons a webpage might really want you to accept some of those cookies, sometimes enough to display a big, content-blocking banner asking you to turn it off. Potentially what you’ve done is just restrict accepting cookies, which is also done without adblockers, but the webpage is making an educated guess. ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [May 5, 2021, 6:39pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/3 "2021-05-05T18:39:53Z")
> [@Yelnick\_McWawa](#): > > What does and ad blocker do for a web browser? Nothing, as the web browser (the software, not the person) doesn’t care. Ad blockers are for our benefit, so we aren’t inundated with advertisements when we simply want to read some Mary Poppins fan-fic (no shaming here). In addition to @naita’s excellent response, most websites don’t even know what ad you would see if you didn’t block them, as they basically sign up with ad vendors who rotate through what shows up in a given spot on the page. So the site is calling a generic ad-url, which is then provided by a third party. On the homepage of the Straight Dope, for instance, you might see an add for Tommy Bahama tropical shirts, while I might see something about furniture from OfficeDepot. Neither are paying the Dope, a third party is, and they are paying either by times seen (hence the request to unblock) or click-through, depending on contract type. > [@Yelnick\_McWawa](#): > > Digitally, I don’t’ think software can differentiate a JPEG porn photograph from an advertisement. The right software can do this all day long. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [May 5, 2021, 6:45pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/4 "2021-05-05T18:45:49Z")
Somebody more techy than I am will be along to correct and elaborate this- It isn’t just a matter of seeing ads. Some ads will install malware or perform other nastiness. An ad blocker prevents that avenue. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [May 5, 2021, 6:47pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/5 "2021-05-05T18:47:42Z")
Just make sure you don’t pick an ad-blocker that _is_ malware. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [May 5, 2021, 7:00pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/6 "2021-05-05T19:00:37Z")
> [@Yelnick\_McWawa](#): > > From a different point: If they want me to look at an advertisement, why not put that advertisement in the form of a JPEG photograph on the web page I’m browsing. Because modern web pages don’t serve ads directly. They contract out to some 3rd party service that auctions off ad space in real time. Part of the way that ad blockers work is that they detect that parts of the page are being served by these ad companies. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [May 5, 2021, 7:06pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/7 "2021-05-05T19:06:46Z")
Ad blockers can make browsers seem snappier because they don’t have to load up all the ads, some of which might even be little videos, etc. They can also save data if you’re on mobile. Another plus – if you’re on mobile and the ads don’t scale correctly, you can’t even see the content. Some pages put “Please turn off your adblocker” in static text under where the ad would go, and that’s why you see that. Others are more aggressive about checking for the presence of an adblocker (I think by seeing if a certain element is shown) and will block you from viewing the content if the element is blocked. Ads have been malware vectors and privacy violators for some time. ---
**Author:** ![Yelnick\_McWawa](https://avatars.discourse-cdn.com/v4/letter/y/839c29/32.png) [@Yelnick\_McWawa](https://boards.straightdope.com/u/Yelnick_McWawa)\ **Post date:** [May 6, 2021, 12:00am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/8 "2021-05-06T00:00:06Z")
OP here - Follow up Q: Why can’t the ad-blocker throw away the advertisement while telling the web page sender that the user was looking at the advertisement. ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [May 6, 2021, 12:38am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/9 "2021-05-06T00:38:13Z")
Because it has no compelling reason to generate money for sites that host advertising. In fact, if it did so, most sites would simply host as many ads as humanly possible while telling everyone to use an ad-blocker. It’s not really sustainable as a market if done that way. ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [May 6, 2021, 12:41am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/10 "2021-05-06T00:41:00Z")
I should note that depending on how the ad is served, the advertiser might not know it was being blocked. If that was universal, all advertisers would simply move to pay per click. ---
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [May 6, 2021, 1:36am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/11 "2021-05-06T01:36:26Z")
> [@Yelnick\_McWawa](#): > > Why can’t the ad-blocker throw away the advertisement while telling the web page sender that the user was looking at the advertisement Look into [AdNauseam](https://adnauseam.io/). It hides ads, and also clicks on some of them. What I want to find is a plug-in that corrupts cookies. It would accept them and then send them back with random (or maybe somebody else’s) content. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 6, 2021, 1:41am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/12 "2021-05-06T01:41:54Z")
> [@echoreply](#): > > (or maybe somebody else’s) content. Oh! I have a little list… ---
**Author:** ![Asuka](https://avatars.discourse-cdn.com/v4/letter/a/dec6dc/32.png) [@Asuka](https://boards.straightdope.com/u/Asuka)\ **Post date:** [May 6, 2021, 6:14am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/13 "2021-05-06T06:14:14Z")
I noticed a lot of websites have ads that will suddenly “pop” into existence midway into the page and disrupt clicking or scrolling if you go over them and they haven’t loaded yet, so an ad blocker will actually make webpage scrolling better . ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [May 6, 2021, 1:20pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/15 "2021-05-06T13:20:10Z")
> [@Yelnick\_McWawa](#): > > …why not put that advertisement in the form of a JPEG photograph on the web page I’m browsing? Way back in the olden days of the early to mid 2000s many ads were just that (or more likely GIFs, whether animated or not). To fit on the page they were generally kept to a few certain specific sizes so they could be swapped easily. The early ad blockers were stupid simple, but also very effective, by blocking any image that fit the standard ad sizes, which were generally wide and short for top or bottom banners, or small squares on the sides. Then the ad blockers started to look for “ad” “adv” “ads” etc. in the filename or path of the image. I would occasionally get one or two sponsors for my own website, and would put up a banner at the top. Since it was self-hosted and linked directly to their website there wasn’t really anything for an ad blocker to latch onto besides the image size, which was easy enough to tweak slightly if I found out it was being blocked. Nevertheless, you get no metrics or tracking by doing this. They can see how many clicks come from your website to theirs, but that’s it, and only if they have something like AWStats set up on their web server and they check it manually. So even going back several years almost nobody self-hosted static ads because “we just can’t make any money doing that” so here we are. Frankly I have little sympathy considering how much this arms race has escalated. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [May 6, 2021, 5:29pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/16 "2021-05-06T17:29:07Z")
I use Adaware and find that the websites that object are mainly news outlets. There is an option to suspend the block for a single visit or permanently for that site. My objection to ads is simply that they clutter up my screen. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [May 6, 2021, 8:18pm UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/17 "2021-05-06T20:18:51Z")
> [@Asuka](#): > > I noticed a lot of websites have ads that will suddenly “pop” into existence midway into the page and disrupt clicking or scrolling if you go over them and they haven’t loaded yet, so an ad blocker will actually make webpage scrolling better . May be off-topic technically, but what I hate are auto-playing videos which have nothing to do with the article I am currently reading. Cracked has started that shite up lately, and pretty much is the final nail in its coffin for me. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [May 9, 2021, 6:10am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/18 "2021-05-09T06:10:31Z")
The better ad blockers can block any element on a page. For Youtube, not only do I block ads, but I also block those 4 boxes that appear near the end of each video, which on older videos hide stuff I want to see. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 10, 2021, 10:32am UTC](https://boards.straightdope.com/t/what-does-an-ad-blocker-do-for-a-web-browser/941454/19 "2021-05-10T10:32:16Z")
> [@John\_DiFool](#): > > May be off-topic technically, but what I hate are auto-playing videos which have nothing to do with the article I am currently reading. Cracked has started that shite up lately, and pretty much is the final nail in its coffin for me. There are extensions that disable auto-play without blocking the vid itself. I use Chrome on my PC and this one seems reliable and lightweight: > **[AutoplayStopper - Chrome Web Store](https://chromewebstore.google.com/detail/autoplaystopper/ejddcgojdblidajhngkogefpkknnebdh)** > > Stops video autoplay gracefully. Of course I also have an ad blocking extension (Adblock Plus) and IME they play well together.