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 developer of AdBlock for Chrome claims to have been inspired by AdBlock Plus, which is a community supported development effort, but otherwise the two efforts are unrelated.