An ad blocker is a small software or browser add-on which prevents the display of online advertising banners or other advertising formats. Filtering is done by recognition of main networks ad server tags.
Ad blockers are used by web users for preventing ad annoyance and intrusivity and are also used in schools and organizations to accelerate navigation and to save bandwidth.
Increasing use of ad blockers becomes an issue for online publishers as it can hurt ad revenues.
Ad blockers usages vary strongly according to countries and according to Internet user profiles. Techy profiles are more enclined to use ad blockers.
Ad blocking rates by countries according to a 2013 Clarity study :
Online publishers have different behaviors with ad blocking phenomenon :
some sue ad blocker editors
some pay to be on ad blocker software whitelists
some try to use ad serving undetected from ad blocking solutions - ie ad stitching.
some prevent ad blocker users to access their content
At the end of 2014, Adblock the leading ad blocking software claimed more than 300 millions of downloads: