is a content-filtering extension
for the Mozilla Firefox
and Mozilla Application Suite
web browsers. Adblock allows users to prevent page elements, such as advertisements
, from being downloaded and displayed.
A forked version called Adblock Plus has risen to replace the old Adblock. It features improvements to the user interface, filter subscriptions, and element hiding. It has become one of the most popular extensions with more than 4 million daily users.
The new Adblock Plus is not an 'upgrade' of the original Adblock; they are separate products with different authors.
Adblock Plus focuses on usability with many new features being added. Its main window has menu items at the top. Also, the list of blockable items is integrated as a panel at the bottom which can be detached from the main window. Element hiding can be used in addition to regular ad blocking. Other new features include filter statistics (hits counter) and the ability to enable or disable individual filters without removing them.
How it works
Like Mozilla's built-in image blocker, Adblock blocks [
] requests according to their source address and can block IFrames
. It also uses automatically-generated user stylesheets to hide elements such as text ads on a page as they load instead of blocking them, known as element hiding.
Michael McDonald created Adblock Plus 0.5 that improved on Adblock by incorporating the following features:
- Support for blocking background images.
- Subscription to filters with a fixed address and automatically update them.
- The ability to hide HTML elements allowing a much greater range of images to be blocked.
- The ability to hide ads on a per site basis instead of globally.
- Memory leak fixes
McDonald discontinued development and transferred the name to Wladimir Palant, who released Adblock Plus 0.6 with a rewritten codebase in January 2006
Basic filter rules can include wildcards represented by asterisks (*). Sites and objects can be whitelisted with filters that start with two at
signs (@@). Regular expressions
delimited by slashes (/) can be used. Adblock Plus also supports a more-sophisticated syntax that gives fine-grain control over filters.
The following is a list of example filters for Adblock.
Blocks the donation banner that appeared on Wikipedia:
Blocks ads in any directory called "banners", or any case insensitive equivalent:
Whitelist a website:
Blocks ads on Yahoo!:
Users can add external filtersets. Adblock Plus includes the ability to use one or more external filter subscriptions that are automatically updated. Filterset.G is incompatible with this system (and Adblock Plus specifically recommends against using Filterset.G for other reasons as well), but other filtersets can added by typing their addresses. A list of known Adblock Plus subscriptions is maintained on the Adblock Plus official website.
- PC World chose Adblock Plus as one of the 100 best products of 2007.
A number of website owners, particularly those whose sites display online advertisements, argue that the use of ad-blocking software such as Adblock is cutting off their revenue stream, with some going as far as calling it tantamount to theft. The central argument against ad-blocking software is that advertisements allow website owners to pay for server upkeep and bandwidth bills to continue hosting their content for free. Some websites have taken counter-measures 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. There have been several arguments supporting and opposing the assertion that blocking ads is wrong. Adblock Plus developer Wladimir Palant
responded to this in his blog. Many other bloggers have also expressed their opinions on this.
With many broadband ISP's like Comcast and Timewarner, now capping or metering their customer's bandwidth, a counter argument for those affected could be that they dislike spending their bandwidth to see annoying advertisements for products they don't want.
-like URL and verifying its delivery and also by more advanced verification of the DOM
after the web page is rendered in the web browser to ensure the expected advertising elements are present.
These methods do not detect the presence of the Adblock extension directly, only the effects of the filters, and are vulnerable to continued updates to the filters, and by whitelist-filtering web scripts with an extension such as NoScript.
An attempt was made to detect the plug-in itself but that detection method was rendered unusable by the 0.7.5.2 update of AdBlock Plus.