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Ad blocking (orad filtering) is asoftware capability for blocking or alteringonline advertising in aweb browser, anapplication or a network. This may be done usingbrowser extensions or other methods, such as browsers with inside blocking.
The first ad blocker was Internet Fast Forward, aplugin for theNetscape Navigator browser, developed by PrivNet and released in 1996.[1][2] The AdBlock extension forFirefox was developed in 2002, withAdblock Plus being released in 2006.[3]uBlock Origin, originally called "uBlock", was first released in 2014.[4]
Online advertising exists in a variety of forms, includingweb banners,pictures,animations, embedded audio and video, text, orpop-up windows, and can even employ audio and videoautoplay.[5] Many browsers offer some ways to remove or alter advertisements: either by targeting technologies that are used to deliver ads (such as embedded content delivered throughbrowser plug-ins or viaHTML5), targetingURLs that are the source of ads, or targeting behaviors characteristic of ads (such as the use of HTML5 AutoPlay of both audio and video).[6]
Use of mobile and desktop ad blocking software designed to remove traditional advertising grew by 41% worldwide and by 48% in the U.S. between Q2 2014 and Q2 2015. As of Q2 2015[update], 45 million Americans were using ad blockers.[7] In a survey research study released Q2 2016, Met Facts reported 72 million Americans, 12.8 million adults in the UK, and 13.2 million adults in France were using ad blockers on their PCs, smartphones, or tablet computers. In March 2016, theInternet Advertising Bureau reported that UK ad blocking was already at 22% among people over 18 years old.[8][9]
As of 2021[update], 27% of US Internet users used ad blocking software, a trend that has been increasing since 2014.[10]
Among technical audiences the rate of blocking reached 58% as of 2021[update].[11]
For users, benefits of ad blocking software include quicker loading and cleaner looking web pages with fewerdistractions,[12][13][14] protection frommalvertising,[15][16][17] stopping intrusive actions from ads,[18][19] reducing the amount of data downloaded by the user,[20][21] lower power consumption,[22][23] privacy benefits gained through the exclusion ofweb tracking,[24] and preventing undesirable websites from making ad revenue out of the user's visit.[citation needed]
Publishers and their representative trade bodies, on the other hand, argue that web ads generate revenue for website owners, enabling them to create or purchase content for their sites. They also contend that the widespread use of ad-blocking software and devices could negatively impact website owners’ revenue.[25]
Ad blocking software may have other benefits to users'quality of life, as it decreases Internet users' exposure to advertising and marketing industries, which promote the purchase of numerous consumer products and services that are potentially harmful or unhealthy[26][27] and on creating the urge to buy immediately.[28][29] The average person sees more than 5000 advertisements daily, many of which are from online sources.[30]
Unwanted advertising can also harm the advertisers themselves if users become annoyed by the ads. Irritated users might make a conscious effort to avoid the goods and services of firms that are using annoying “pop-up” ads that block the Web content the user is trying to view. For users not interested in making purchases, the blocking of ads can also save time. Any ad that appears on a website exerts a toll on the user's "attention budget" since each ad enters the user's field of view and must either be consciously ignored or closed, or dealt with in some other way. A user who is strongly focused solely on reading the content they are seeking likely has no desire to be diverted by advertisements that seek to sell unneeded or unwanted goods and services.[31] In contrast, users who are actively seeking items to purchase might appreciate advertising, in particular targeted ads.[32]
Another important aspect is improving security; online advertising subjects users to a higher risk of infecting their devices withcomputer viruses than surfing pornographywebsites.[33] In a high-profile case, the malware was distributed through advertisements provided toYouTube by a malicious customer ofGoogle'sDoubleClick.[34][35] In August 2015, a0-day exploit in the Firefox browser was discovered in an advertisement on a website.[36] When Forbes required users to disable ad blocking before viewing their website, those users were immediately served with pop-under malware.[37] TheAustralian Signals Directorate recommends individuals and organizations block advertisements to improve theirinformation security posture and mitigate potentialmalvertising attacks and machine compromise.[38] The information security firmWebroot also notes employing ad blockers provides effective countermeasures against malvertising campaigns for less technically sophisticated computer users.[39] Ad blocking is recommended by theFBI to prevent online scams.[40]
Ad blocking reduces page load time and saves bandwidth for the users. Users who pay for total transferred bandwidth ("capped" or pay-for-usage connections), including most mobile users worldwide, have a direct financial benefit from filtering an ad before it is loaded. Using an ad blocker is a common method of improving internet speeds.[41] Analysis of the 200 most popular news sites (as ranked byAlexa) in 2015 showed thatMozilla Firefox Tracking Protection led to a 39% reduction in data usage and a 44% median reduction in page load time.[42] According to research performed byThe New York Times, ad blockers reduced data consumption and sped upload time by more than half on 50 news sites, includingThe New York Times itself. Journalists concluded that "visiting the home page of Boston.com (the site with most ad data in the study) every day for a month would cost the equivalent of about $9.50 in data usage just for the ads".[43]
It is a known problem with most web browsers, includingFirefox, that restoring sessions often plays multiple embedded ads at once.[44] However, this annoyance can easily be averted simply by setting the web browser to clear all cookies andbrowsing-history information each time the browser software is closed.[citation needed] Another preventive option is to use a script blocker, which enables the user to disable all scripts and then to selectively re-enable certain scripts as desired, in order to determine the role of each script.[citation needed] The user thus can very quickly learn which scripts are truly necessary (from the standpoint of webpage functionality) and consequently which sources of scripts are undesirable, and this insight is helpful in visiting other websites in general.[citation needed] Thus by precisely controlling which scripts are run in each webpage viewed, the user retains full control over what happens on their computer CPU and computer screen.[citation needed]
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One method of filtering is simply to block (or prevent auto play of)Flash animations (though these are now largely obsolete) or image loading orMicrosoft Windows audio and video files. This can be done in most browsers easily and also improves security and privacy.[45] This crude technological method is refined by numerousbrowser extensions. Everyweb browser handles this task differently, but, in general, one alters the options, preferences or application extensions to filter specific media types. An additional add-on is usually required to differentiate between ads and non-ads using the same technology, or between wanted and unwanted ads or behaviors.
Some browsers include built-in controls to block unsolicited pop-up windows as part of their content-blocking features. For example, Brave exposes a setting to block pop-ups in its privacy and security options.[46]
The more advanced ad-blocking filter software allows fine-grained control ofadvertisements through features such asblacklists,whitelists, andregular expression filters. Certain security features also have the effect of disabling some ads. Someantivirus software can act as an ad blocker. Filtering by intermediaries such asISP providers or national governments is increasingly common.
As of 2015[update], many web browsers block unsolicitedpop-up ads automatically. Current versions ofKonqueror,[47]Microsoft Edge,[48] andFirefox[49][50] also include content filtering support out-of-the-box. Content filtering can be added toFirefox,Chromium-based browsers,Opera,Safari, and other browsers with extensions such asAdBlock,Adblock Plus, anduBlock Origin, and a number of sources provide regularly updated filter lists. Adblock Plus is included in the freeware browserMaxthon from thePeople's Republic of China by default.[51]
Another method for filtering advertisements usesCascading Style Sheets (CSS) rules to hide specificHTML andXHTMLelements. This was once handled directly by a browser's user style sheet and custom CSS files. The CSS files employed regular expressions to describe a general advertisement profile. An example CSS selector from the once popular Floppy Moose (2003) style sheet is below.[52] It simply hides anything with a link containing the characters "ad."[53]
a:link[href*="ad."]img
Stylesheets are still used to block ads today. However they are almost always used by an ad-blocking extension that combines CSS with other techniques. AdBlock Plus syntax includes CSS selectors which they call "element hiding" rules.[54] The newer uBlock Origin even allows "cosmetic filters" which inject custom CSS declarations.[55] Due to changes in advertising techniques, modern ad-blockers use more specific selectors, more frequently updated selectors, and a greater quantity of selectors. For example, the Floppy Moose style sheet originally contained 40 lines of CSS. In 2022, Easylist contains thousands of CSS selectors. In contrast to the general example above, below is one of the many specific CSS selectors from Easylist (2022).[56]
a[href^="https://topoffers.com/"][href*="/?pid="]
In January 2016,Brave, a free, ad-blocking browser for Mac, PC, Android, and iOS devices was launched. Brave users can optionally enable Brave's own ad network to earnBasic Attention Tokens (BATs), a type of cryptocurrency, which can be sent as micro-payments to publishers.[57]
At the beginning of 2018, Google confirmed that the built-in ad blocker for theChrome/Chromium browsers would go live on 15 February:[58] this ad blocker only blocks certain ads as specified by theBetter Ads Standard[59] (defined by the Coalition forBetter Ads, in which Google itself is a board member).[60] This built-in ad blocking mechanism is disputed because it could unfairly benefit Google's advertising itself.[61]
In 2019, bothApple and Google began to make changes to their web browsers' extension systems which encourage the use of declarative content blocking using pre-determined filters processed by the web browser, rather than filters processed at runtime by the extension. Both vendors have imposed limits on the number of entries that may be included in these lists, which have led to (especially in the case of Chrome) allegations that these changes are being made to inhibit the effectiveness of ad blockers.[62][63][64][65]
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A number of external software applications offer ad filtering as a primary or additional feature. A traditional solution is to customize anHTTP proxy (or web proxy) to filter content. These programs work by caching and filtering content before it is displayed in a user's browser. This provides an opportunity to remove not only ads but also content that may be offensive, inappropriate, or even malicious (Drive-by download). Popular proxy software which blocks content effectively includeNetnanny,Privoxy,Squid, and somecontent-control software. The main advantage of the method is freedom from implementation limitations (browser, working techniques) and centralization of control (the proxy can be used by many users). Proxies are very good at filtering ads, but they have several limitations compared to browser-based solutions. For proxies, it is difficult to filterTransport Layer Security (TLS) (https://) traffic and full webpage context is not available to the filter. As well, proxies find it difficult to filterJavaScript-generated ad content.
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Mostoperating systems, even those which are aware of theDomain Name System (DNS), still offerbackward compatibility with a locally administered list of foreign hosts. This configuration, for historical reasons, is stored in a flat text file that by default contains very few hostnames and their associatedIP addresses. Editing this hosts file is simple and effective because most DNS clients will read the local hosts file before querying a remoteDNS server. Storingblack-hole entries in the hosts file prevents the browser from accessing an ad server by manipulating the name resolution of the ad server to a local or nonexistent IP address (127.0.0.1 or0.0.0.0 are typically used for IPv4 addresses). While simple to implement, these methods can be circumvented by advertisers, either by hard-coding, the IP address of the server that hosts the ads (this, in its turn, can be worked around by changing the local routing table by using for exampleiptables or other blocking firewalls), or by loading the advertisements from the same server that serves the main content; blocking name resolution of this server would also block the useful content of the site.
Using aDNS sinkhole by manipulating the hosts file exploits the fact that most operating systems store a file with IP address, domain name pairs which is consulted by most browsers before using a DNS server to look up a domain name. By assigning theloopback address to each knownad server, the user directs traffic intended to reach each ad server to the local machine or to a virtual black hole of/dev/null orbit bucket.
Advertising can be blocked by using a DNS server which is configured to block access to domains or hostnames which are known to serve ads by spoofing the address.[66] Users can choose to use an already modified DNS server[67][68][69] or set up a dedicated device running adequate software such as aRaspberry Pi runningPi-hole themselves.[70] Manipulating DNS is a widely employed method to manipulate what the end-user sees from the Internet but can also be deployed locally for personal purposes. China runs its ownroot DNS and the EU has considered the same.Google has required theirGoogle Public DNS be used for some applications on itsAndroid devices. Accordingly, DNS addresses/domains used for advertising may be extremely vulnerable to a broad form of ad substitution whereby a domain that serves ads is entirely swapped out with one serving more local ads to some subset of users. This is especially likely in countries, notablyRussia,India andChina, where advertisers often refuse to pay for clicks or page views. DNS-level blocking of domainsfor non-commercial reasons is already common in China.[71]
OnAndroid, apps can run a localVPN connection with its own host filtering ability and DNS address without requiringroot access.[72] This approach allows ad blocking app to download ad blocking host files and use them to filter out ad networks throughout the device.AdGuard, Blokada,[73] DNS66,[74] and RethinkDNS[75][76] are few of the popular apps which accomplish ad blocking without root permission.[citation needed] The ad blocking is only active when the local VPN is turned on, and it completely stops when the VPN connection is disconnected.[citation needed] The convenience makes it easy to access content blocked by anti-adblock scripts.[citation needed]
This approach optimizes battery usage, reduces internet slowdown caused by using external DNS or VPN ad blocking and needs overall less configuration.[citation needed]
Devices such as AdTrap[77] orPi-hole use hardware to block Internet advertising. Based on reviews of AdTrap, this device uses aLinuxKernel running a version of PrivProxy to block ads fromvideo streaming,music streaming, and any web browser,[78] while PiHole acts as a local DNS to block advertisement servers, stopping connected devices from showing most ads. Another such solution is provided for network-level ad blocking for telcos by Israeli startup Shine.[79]
Internet providers, especially mobile operators, frequently offer proxies designed to reduce network traffic.[80] Even when not targeted specifically at ad filtering, these proxy-based arrangements will block many types of advertisements that are too large or bandwidth-consuming, or that are otherwise deemed unsuited for the specific internet connection or target device. Internet service providers have been known to block advertisements while at the same time injecting their own ads promoting their services.[81]
Some content providers have argued that widespread ad blocking results in decreased revenue to a website sustained by advertisements[82][83] ande-commerce-based businesses, where this blocking can be detected.[citation needed]
Tools that help block ads have to work on different business models to stay in operation:
Some websites have taken countermeasures against ad blocking software, such as attempting to detect the presence of ad blockers and informing users of their views, or outright preventing users from accessing the content unless they disable the ad blocking software, whitelist the website, orbuy an "ad-removal pass". There have been several arguments supporting[88] and opposing[89] the assertion that blocking ads is wrong.[90] Indeed, there is evidence to show that these countermeasures may hurt a website'sSEO performance, as users unwilling to turn off their AdBlock may instead go to a competitor's website listed in the search results.[91] Due to the little amount of time the user spends on the website, and the greater time spent on a competitor's, search engines may view the webpage less favourably and reduce its search ranking.[92] The back-and-forth elevation of technologies used for ad-blocking and countering ad-blocking have been equated to an "ad blocking war" or "arms race" between all parties.[93][94]
It has been suggested that in theEuropean Union, the practice of websites scanning for ad blocking software may run afoul of theE-Privacy Directive.[95] This claim was further validated by IAB Europe's guidelines released in June 2016 stating that there indeed may be a legal issue in ad blocker detection.[96] While some anti-blocking stakeholders have tried to refute this[97][98] it seems safe to assume that Publishers should follow the guidelines provided by the main Publisher lobby IAB.
In August 2017 a vendor of such counter-measures, Admiral, issued a demand under section 1201 of the U.S.Digital Millennium Copyright Act for the removal of adomain name associated with their service from an ad-blocking filter list. The vendor argued that the domain constituted a component of atechnological protection measure designed to protect a copyrighted work, which made it a violation ofanti-circumvention law to frustrate access to it.[99][100]
In September 2023, after a 4 month testing period, the American video hosting siteYouTube began implementing countermeasures to viewers using adblocker software to watch videos on its platform. A popup message appeared warning that the user was breaching the terms of service, and may be blocked from accessing content after three videos unless they whitelisted the site, or purchasedYouTube Premium. This sparked extreme controversy and backlash across the YouTube communities.[101][102][103] In October 2023, privacy advocate Alexander Hanff filed a criminal complaint against YouTube under Irish jurisdiction due to its ad blocking detection script, which is believed to violateEuropean Union privacy laws.[104] In June 2024, YouTube began experimenting withserver-side ad insertion,[105] which consists of embedding ads directly into video streams, making automatic blocking significantly more difficult.[106][107]
As of 2015[update], advertisers and marketers look to involve their brands directly into the entertainment withnative advertising andproduct placement (also known as brand integration or embedded marketing).[108] An example of product placement would be for a soft drink manufacturer to pay areality TV show producer to have the show's cast and host appear onscreen holding cans of the soft drink.[109] Another common product placement is for anautomotive manufacturer to give free cars to the producers of aTV show, in return for the show's producer depicting characters using these vehicles during the show.[citation needed]
Some digital publications turned to their customers for help as a form oftip jar.[citation needed] For example,The Guardian is asking its readers for donations to help offset falling advertising revenue. According to the newspaper's editor-in-chief, Katharine Viner, the newspaper gets about the same amount of money from membership and donations as it does from advertising.[110] The newspaper considered preventing readers from accessing its content if usage of ad-blocking software becomes widespread,[111] but so far it keeps the content accessible for readers who employ ad-blockers.[citation needed]
A new service called Scroll, launched in January 2020, worked with several leading website publishers to create a subscription model for ad-free browsing across all supported websites. Users would pay Scroll directly, and portions of the subscription fees are doled out to the websites based on proportional view count.[112]
Block Internet advertisements using web browser software (and web content filtering in the gateway), due to the prevalent threat of adversaries using malicious advertising (malvertising) to compromise the integrity of legitimate websites to compromise visitors to such websites. Some organisations might choose to support selected websites that rely on advertising for revenue by enabling just their ads and potentially risking compromise.
While many websites need advertisements to stay online, we have seen more and more popular websites (i.e. millions of visitors a year) infecting customers due to 3rd party hosted adverts on their websites – malvertising. [...] Ad blocker plugins can be installed and left without any user input and are very useful for stopping less technical users from being infected.
