|Initial release||December 8, 2009|
|Stable release||2.5.63 / May 3, 2013|
|Development status||In development|
AdBlock is a content-filtering and ad blocking extension for the Google Chrome, Apple Safari, and Opera web browsers. AdBlock allows users to prevent page elements, such as advertisements, from being displayed. AdBlock is currently the most popular extension for Google Chrome. It currently has more than 15,000,000 users. According to an article in The New York Times, the extension was created on December 8, 2009 (the day that support for extensions was added to Google Chrome). Safari support was added in June 2010.
AdBlock is not to be confused with Adblock Plus, the Chrome version of the popular Firefox plugin, which is a merge of the source code of former Chrome plugin AdThwart and Adblock Plus' Firefox version.
Version History 
Version 2.1 added internationalization. Currently, AdBlock supports over 28 languages.
Version 2.4 saw many speed improvements - reportedly, the extension is twice as fast, while loading less memory per tab.
As of Version 2.5, the add-on blocks the download of all advertising resources, including ads in videos and in Flash.
AdBlock uses the same filter syntax as Adblock Plus for Firefox and natively supports Adblock Plus filter subscriptions. Filter subscriptions can be added from a list of recommendations in the "Filter Lists" tab of the AdBlock options page, or by clicking on an Adblock Plus auto-subscribe link.
Users can also add their own filters in the "Customize" tab of the options page; they can be added automatically from the right click or toolbar menus.
On April 1, 2012 the developer changed the code to display LOLcats instead of simply blocking ads. Initially developed as a short-lived April Fool, the response was so positive that CatBlock is now an optional add-on supported by a monthly subscription.