Adblock Plus is an extension for Firefox, Thunderbird, and several other applications with the primary goal of removing advertisements. For that, it will look at all requests made by web pages and block the request if the address the request should go to matches a filter in Adblock Plus.

Adblock Plus, an easy-to-use free addition to the Firefox Internet browser that deletes advertisements from Web sites is still a niche product for the niche browser. But it is potentially a huge development in the online world, and not because it simplifies Web sites cluttered with advertisements.

"GNU IceCat, formerly known as GNU IceWeasel,[1] is a web browser distributed by the GNU Project. IceCat is a fork of Mozilla Firefox which is made entirely of free software..."

"GNU IceCat 3.0.8-g1 has been released! GNU IceCat is the GNU version of the Mozilla Firefox browser. This new version includes all the changes made in Firefox 3.0.8..." -- See also Free Addons for IceCat

"I am pleased to announce the new version for the GNU IceCat web browser. GNU IceCat is based on the Mozilla Firefox source code. While the basic Mozilla Firefox source code is free software, and we thank them for their significant contributions to the community, some non-free files are distributed in the Firefox source tree, and Firefox can recommend non-free plugins. IceCat is entirely Free Software..."

GNU IceCat is the GNU version of the Firefox browser. Its main advantage is an ethical one: it is entirely free software. While the Firefox source code from the Mozilla project is free software, they distribute and recommend non-free software as plug-ins and addons. In addition, GNU IceCat includes some privacy protection features, included in a separate addon.

It's almost exciting as Alien vs. Predator, only a little more sad. It's a tale of two Firefox addon developers, Giorgio Maone wielding Noscript and Wladimir Palant brandishing Adblock Plus, crossing swords in a battle of egos and subterfuge, while the poor world of Firefox users watched in consternation.

GNUzilla is the GNU version of the Mozilla suite, and GNU IceCat is the GNU version of the Firefox browser. Its main advantage is an ethical one: it is entirely free software. While the Firefox source code from the Mozilla project is free software, they distribute and recommend non-free software as plug-ins and addons. In addition, GNU IceCat includes some privacy protection features.

Why is it hard for people to understand that there is nothing called "Free Lunch"? Somebody was concerned, that adblock is ruining their revenue by blocking the ads (shown on the website). And at the same time, not providing the website owners, the ability to block adblock users.